lay bathroom wall tiles

I am remodeling my bathroom by replacing the old bathtub with a toilet suite, therefore I have removed the bathtub and wall tiles. ( it's an old double brick house built in 1960s)
1. Do I need to do anything before lay the new wall tiles? (See attached image, It looks not too bad to me, reasonable clean and flat)
2. Since I have remove the bathtub and subfloor for plumber come to dig drains for toilet suite, it's soil floor at the moment (see attachment), how to redo the sub floor before lay the new floor tiles?




Regards,
Jamie