Bathroom Improvement

I want to upgrade
(i) my shower stall walls to tile , nice tiles
(ii) Shower door
I live in Northern California.
Anyone with experience please let me know how much it costs.

I have large (8in x 8in) ceramic tiles on my bathroom floor that came loose. The grout is cracked and now water that splashes out of my shower stall gets underneath it. I don’t want mold to develop under the tiles. I want to know how I can fix the tiles permanently and prevent water from getting underneath them. I have about 5 tiles that are now with cracked grout and with water underneath. They are white tiles with no fancy designs on them. Would adhesive caulk alone work? If not, what do I need to fix them and how do I do it? Thanks!