Biting point or gas first?

Beginners have to rev the engine a little at first till you learn just where the clutch begins to engage. You will also have this every time you drive a different standard shift vehicle.

The best way to learn a manual transmission is to practice backing up. The gear ratio is is much lower and thus it's easier to learn.

It's an almost simultaneous action, but breaking it down, I set the gas first. If you over engage the clutch with too few revs, then you can stall out. And look like a noob.

That would be correct as long as you don’t get the habit of slipping that clutch. The car will roll forward with no gas, so you can train yourself to let the clutch out then gas.

If that is what a professional instructor is telling you then yes it is correct.

Yes. Hold the bite before depressing the accelerator.

Set the gas ?
Turn the engine on, find biting point on clutch put into gear and move forward.