I set tubs all the time for work.
Prep the walls by making them plumb and flat. Furring strips w greenboard or hardiboard, or just use construction adhesive to bond the board to the walls. What's the opening size? 60x32 ish or are you going w a larger soaking tub?
Fiberglass tubs get screwed to the wall through the tub flange, or with clips they provide. Depends on manufacturer. Cast iron tubs don't get screwed to the wall, they have screws holding them down that are screwed into the wall right above the edge of the tub flange. Pre drill holes of using a fiberglass tub.
Are you dead set on tiling walls? A fiberglass 3 panel surround might be adequate.
Tub gets set in a bed of mortar. Even the ones that say they have a foam foot and don't need it. Put a sheet of plastic down on the floor, then lay your mortar bed on top of the plastic. The plastic means the tub and mortar set together but the mortar won't bond to the floor and be a major headache to remove in ten years. The mortar gives a good footing and the shower spraying on the bottom of the tub does t sound hollow and cheap. It also prevents breaking the bottom out of the tub.
I have all the answers you'll need. Just ask.