Can I plug my computer on a power strip?

Amps * Volts = Watts.

So, say your computer has a 600 watt power supply.
The wall has 110 volts.

So 600 watts / 110 volts = 5.45 amps max that the computer will draw.

Do similar math with your charger or monitor and you'll see if you come close to 13 amps.

I suspect you'll be fine, but it won't hurt to check it just to be sure.

Yes, providing you don't load the strip or the cable down with more than 13 Amps. total.

It depends on your surge protector. Check the surge protector too see how many watts it can handle, and then check each of your items plugged in to see what the total wattage is for them. If your wattage is below the recommended value of the powerstrip you will be fine. If it exceeds this I would recommend buying another powerstrip, or just plugging your fridge straight into the wall. Normally a fridge doesn't need to be connected, it's your laptop you should be more concerned with (power spike could damage your laptop and it's data)