My house was built in 1930 and has the original 3x6 subway tile in the BR. Most of the tile is in good condition except for 2 small walls that has missing, broken, cracked or discolored tile. I would like to replace this tile but am wondering how difficult a job it is. I would only be interested in replacing the field tile since that is where the problem lies AND, at least at subway tile.com, they do not carry the particular shaped tile that tops the wall that I would need. The tile does not seem to be attached to the mud job but rather just stacked, one on top of another, with very small grout spaces and grout that looks like cement (grey color as in cement). My questions are: How difficult is this to do, how would I cut the grout lines (tool and method), can I stack it the way they originally did without using an adhesive, and finally, what type of grout would I use to match the existing grout? BTW, the mud job appears to be in good shape from what I can see of it. Thanks for your help.