My shower walls are around a combination shower tub. My walls are brick. Can I just paste on ceramic glass tile on top of the white ceramic tile shower walls?

The shower-tub is attached directly to the wood studs. when we remove it, there won't be any sheet rock attached to the studs. What do we use, sheet rock or something else to fill in the void. How do we make sure the walls will be water proofed before we install the tile? What's the best tile to use (size) and other features?