How to install wallboard and tile around Fiberglass Tub and shower unit?

Wallboard installation is pretty much the same if there wasn't a tub and shower unit. I'm assuming there is no drywall up right now and the unit is installed right on the studs. If this is the case, then you would install the wallboard as any other but keep it about a 1/2" or so from the tub surface. This will keep water from getting under the wallboard and getting trapped there. When you install the tile over the wallboard, keep this up from the surface of the tub as well to avoid getting water trapped. Make sure you use waterproof drywall or "greenboard". It is more resistant to moisture, a big issue in a bathroom with a tub/shower.

in most cases the sheet rock goes under the surround

those that it goes over have 1" - 2" wide lips around them that you overlap the sheet rock on. It will cost a little more but use moisture resistant sheet rock only (sometimes called blue board because of the color of it.) Just install the wall board as you normally would to the walls and finish it the same way as well.

There should be instructions as per specifics with the tub/shower unit. read and follow them. if there are non check with your supplier for this.

The reason for the special wall board is that regular wall board hold moisture and will become a home for mold and mildew in as little as 6 months.

The tile will go on over the sheet rock. It may also require a third type of board (called tile board or concrete board.) Again your supplier should know which type you need depending on the kind of tiles you use.