Flooring Tile - Tile preparation question

I am installing wall tile in a bathroom on newly installed greenboard. My question is whether I need to tape and mud the seams and nail holes on the area that will be tiled. Also, at the corners of the walls, do I use grout or a flexible caulk? Thanks for the help.

Well, if this is a wet area (tub surround, shower walls) then rip it out it should not be there and replace with a moisture retarder and cement board, this is not an argueable point, it's a must and a code violation as of Jan 2006. If it's outside the wet areas, then tape the joints and tile away. Use matching caulk, not grout in the corners, but if you have faced insulation or a vapor barrier installed behind it, pull it down, remove the vapor barrier or slice the insulation facing and reinstall before proceeding. Otherwise it will rot from the back side out.

Thanks. Yes, it is outside the wet areas. I have a 3-piece fiberglas surround. One more question: I have cove base tiles for the base of the walls where they meet the floor, should the joint between them (the cove and floor tile, that is) be caulk also, or do I use grout there.

One more question: Do I need to tape the corners before tiling? I'd like to leave them un taped so they stay square. The mud will make them lose their squareness.

ANY change-in-plane should be caulked no matter where it is. Inside corners wouldn't need to be taped.:)