Is this meant to just be for adhesive and joint compound or does another product have to be used for joints and is it easy to clean off the tiles?

Hello James, Type 1 Mastic is a tile setting material. Some cement board manufacturers approve it for the board joints, but we do not recommend it in that application. We recommend a polymer-modified mortar for board joints, and in many cases, the tile as well. Keraflex Plus is a fantastic option that Lowe's sells. If you have large tiles Type 1 is not recommended. Mastics cure by evaporation and need open grout joints to gain strength. The larger the tile the longer it takes to set up so it's not the best option in every case. If it's a backsplash with small tiles (no glass), it's fine just wait several days before grouting. Please feel welcome to call Product Support at (800) 992-6273 if you wish to discuss this further.