My kitchen wall above the countertop has 1/2" primed drywall with electrical outlets. Can I use ceramic tile throughout that area and behind the stove over the drywall if it is solid? What do I need to do about the Painted Surface, if anything?

I am contemplating laying 1500 - 2000 sq. ft. of tile on concrete slab. I have to rip up a combination of carpet, existing (ugly) ceramic tile, and parquee. The tile I am considering is 18x18 ceramic. I have not done tiling before but am fairly capable at DIY. The reason for this message is to get input on any gotchas I may run into, on how long it may take to (1) rip up the existing flooring (2) lay the tile - how much can I get done in a weekend (3) grout and cleanup How concerned do I have to be about the floor being level; does the adhesive fill minor uneveness or do I need to use some sort of leveling compound? When laying tile in bathrooms does the adhesive have to be waterproof? What kind of equipment do I need to cut 18x18 tiles?