For those into photography... How long until I should upgrade from my rebel t5?

Sounds like you have a bunch of camera noob friends. A new body won't do much to improve your images. You need to ask yourself what a newer body will do for you. What will improve your images is good lenses and learning how to improve your skills. With photography, no matter what your skill level, you can always improve.

1. As you wisely know, lots of pixels doesn't necessarily make for a better camera. Unless you're going to make billboard sized prints, going above 16 Mp doesn't buy you much, especially if you view it on a computer monitor. For a given sensor technology, one should stay below a certain number of pixels. More pixels means the area of each pixel is smaller which degrades color depth, dynamic range, sensitivity, and increases noise. With improvements in sensor technology, higher pixel density is possible.

2. Add-on lenses you screw on to your lens suck. Image quality (clarity, distortion, focus flatness, contrast) will degrade. Extension tubes work well if you want want to save money.
If you have the money, a macro lens will give you excellent clarity, almost no distortion, and a flat focus field. If you spring for a macro lens, something in the 100mm focal length arena works well. Third party lenses (Tokina, Tamron, Sigma) all have excellent macro lenses that cost much less than a Canon macro. Don't buy a zoom lens that says it's a macro - it isn't!!!!

3. Getting a newer camera won't do much for this. Use bulb mode. Your camera has this. Look it up in your camera manual.

4. Question makes no sense. All cameras have a shutter release. They work as intended on all models, even cheapo Buzz Lightyear cameras. Perhaps you're thinking about cable releases? Entry level cameras generally don't have cable releases these days. You can get a remote for your camera which is nice for taking macro shots.

Andrew took my answer ! LOL ...
I still shoot with my Nikon D80 / D5000 . And most of the time I can match the work of the guys shooting with their $6,000 D4 ...I've done glamour studio shoots where I equaled the shots of those shooting with a full frame camera .
You still have a couple of years to master what you already have .
Try going to youtube and check out the many photography videos they have . I'm there almost everyday .

When it dies.

1) Pixels just means how large of a print you can make from the file. It doesn't necessarily mean that the image on the screen or a 4x6 print would be any sharper. More pixels on an APS-C sensor means that they have to be smaller in order to fit more within the same area. The smaller the pixel, the more noise you'll get and the lower the dynamic range of the sensor. This is how a 12MP Sony A7S will have much less noise and much more dynamic range than a 36MP Nikon D810. Those who often need no noise at high ISO, they'll choose the A7S. Those who often print larger than 11x14 will choose a camera like the D810. For this reason, if you should need a lot of pixels, it's best to go with a full-frame camera since the sensor is larger allowing for more and bigger pixels.

2) Macro can be achieved in a variety of ways. The absolute best way is to get a real macro lens as opposed to a lens "with" macro. A lens "with" macro will be able to reach magnifications up to about 1:4 (quarter life size). A true macro lens will reach a magnification of 1:1 or life size. The size is referring to how large the image will be projected onto the sensor. Take a photo of a stamp that's 1" square. With the 1:4 macro, it'll be .25" on the sensor, while the true macro will project a 1" square. The benefits of a macro is that you have full AF from minimum to infinity, the optical quality is very high, and you can photograph a very small area. Macro lenses come in different focal lengths from 50mm to 180mm. They all photograph the same amount of area. With a 50mm you may be about 1' away, while with a 100mm you could be 2' away - both lenses capturing the same area. the benefit is when photographing skittish subjects like dragon flies. Being further away will prevent you from frightening your subjects.

The next best way to get macro is with an extension tube such as these: http://www.bhphotovideo.com/c/search?Ntt=EF+extension+tube&N=0&InitialSearch=yes&sts=ma&Top+Nav-Search=
Because an extension tube does not have any elements, you do not loose any optical quality. Just attach it between your existing lens and the body, and you now have a rig that can focus very close. The down side is that if you're using a short lens like a 55mm, your working distance is quite close. Therefore, it's best to use extension tubes on at a 55mm lens, but longer would be better. The tube basically limits the focusing of the lens to very close distances.

Another option that doesn't loose any image quality is a reversal ring. I do not recommend them because you no longer have control over the aperture.

Lastly is the close up filter or a diopter. Basically just a filter that makes your lens focus close. Like with the extension tube, your focusing range is limited to a narrow area. Depending upon brand, the close-up filter will lower the image quality. By how much and will you notice it depends upon the quality of the filter, and of course, how critical of an eye you have.

3) Long shutter speeds on your T5i is no different than any other DSLR at any price. As you state, your T5i will automatically go as slow as 30-second exposure. If you need a longer exposure, then you'd use Bulb mode. When in Bulb mode, you press the shutter release (preferably on a cable release or remote and the actual shutter button to prevent motion blur), the shutter opens and stays open until you release the shutter button. Cameras will often provide the ability to change how this works. Default is: Press the shutter button down and the shutter stays open until you release it. I prefer to switch the mode to where I press the shutter button once to open the shutter and a second time to close it. This way I don't have to keep the button pressed down. With Bulb mode, you can take exposures 20, 30, 60 minutes or more.

4) The cable release socket for each brand, and even each model within one brand all are different. Therefore, you need to get a cable release designed specifically for your camera. It certainly does not have to be made by Canon. In fact, many off brands are just as good and cheaper, some offering more features such as an intervalometer.

2) try extension tubes if you want macro on a budget. A tripod and additional lighting may be useful, especially if you're using a small aperture to get a reasonable depth of field.
3). If you get a cable release and set the exposure mode to B you can have any exposure you want up to hours, if the battery doesn't die.

4) ? Most cameras have different button layouts. Not sure what you mean by not compatible?

You might wasn't to upgrade after less than one year?! Crazy. You will only just have got to know all things which that camera can do for you.

More pixels? All DSLRs on the market today have more Mps than you need, except at the very top end of professional use.

Your camera has one shutter button - what do you mean by "shutter buttons not compatible"?

What do you find that frustrates you about your present camera?

Slower shutter speeds? Remember that just 20 years ago nearly all cameras did not go much slower then 1 or 2 seconds. You can always use the Time or Bulb setting for huge long exposures - check your handbook for the procedure..

Screw-on so-called "macro lenses" are a waste of money. only a true "macro lens", one which totally interchanges with any other lens for that camera, is going to give you high-quality close-up images.

DSLR photography doesn't need to be over-complicated. This online photography course has been developed for beginners - intermediate levels and will teach you how to make the best use of your DSLR camera. https://tr.im/WBQC6

Learning how to confidently use your DSLR will help you get full value out of this awesome camera you have already paid for!

This course has been developed after seeing many potential photographers give up far too soon, wasting good money they have spent on the purchase of their DSLR camera.

Maybe just keep it and upgrade your lens?

1. You are correct. Megapixels is just picture size. Since you don't blow up your pictures to bus sizes, you don't need to upgrade.
2. Your camera can take high quality shots. It depends mostly on your skill but a screw-on lens adapter lowers picture quality. If you want to do high quality macro, buy a real macro lens. If your lens already has macro capability then that's it.
3. Longer shutter speeds? There's always B mode and your wall clock.
4. Your camera has a shutter button. Your camera can use remote controls. Your camera can even use a battery grip.

As long as it works and produces results you can live with,
there is no reason to upgrade.

As long as it works and produces results you can live with,
there is no reason to upgrade.