Yes, as long as your drywall is in good shape, you can tile it.
I'm not a pro but pretty close to it. I've done it many times, and I am about to do it tomorrow.
I would not do this in a shower or tub surround where there will be lots of water.
Yes, as long as your use drywall heavy enough to support the weight of your tile, you should be golden.
Yes
Replace the drywall with tile backer.
You need a level surface so you would want the joints to be done & dry. HOWEVER you really shouldn't put tile over drywall. Cement board, HardiBacker or green board, but never drywall.
It's no different on drywall than it is on any other surface. You spread the cement the same way, you apply the tile the same way.
You use a regular wall tile adhesive like Ecobond
NO, you might think so at first, but the tile will fall off.
Tile is glued onto a surface and then grouted. Both of these processes make it stay put very well. You can break it up with a sledge hammer, but then you will also need to replace the drywall. If you are redoing a shower or bath area, replacing the drywall usually needs to be done anyway.
Sometimes used for maintaining cleaner floor surfaces when installing drywall and drywall finishing. Also used over exterior tile to prevent silt from entering tile.
Soak it in a tub of water for a few days, then the drywall can be scraped off.
Use a good mastic or adhesive
Yes, you can by using standard tile adhesive.
Yes. This gives you a surface to apply the tile.
Mildew proof drywall is best out of drywall choices, -but much better still is concrete/fibre board. These are now plentiful and low cost, totally impervious to water and great for tile. Last time I was in Home Depot they had 3 kinds. I always these around bathtubs or shower areas.