Bathtub lip protrudes and are not aligned with plates. He is on the wall opposite the shower faucet, how I can tile? Perhaps only the tile slope? It will look a bit weird because the plate not going to be sitting in the band starting in this field, but there will be a front vanity is not noticeable. I am interested builiding mortar quite well because at this time the bottom the slab is not a good coverage.

You can fix it, but it will be difficult and perhaps no work in the end. It also seems that this is a bathtub Shower can mean an incorrect revision of moisture can cause problems, perhaps not directly but by the buildup of mold, etc. It is good that you can start using correct a plumb wall to make it right from the start.