Does the joint where the glass wall tile meets the deck need a special glass molding? I would prefer none just glass tile to solid surface. You can run the wall tile right to the tub deck, and caulk the intersection with color and texture matched caulk. Borders/liners are added for aesthetic and transitional interest. Sometimes it's purely design, sometimes for function, sometimes a combination. If your glass tile can stand on its own, and you'd prefer it to do so, then let it. I've not ever seen a glass grab bar or hand rail. Clear polycarbonate (I think it was PC) yes, but glass, no. Mongo

Ameriwall has a tub surround with a 72" back wall. It can be cut down for a smaller tub. Might be others, that's the first one I found. 7230TA

My first step would be to recommend you go to the manufacturer's website and get the specific framing/attachment instructions for your tub. Your tub might need a horizontal 2x4 ledger just under the 60" flange for support, and the flange itself may or may not be screwed into the wall studs. That will dictate how close the flange needs or does not need to be to the framing. As to the flange detail, you'll first cover the studs with a barrier, usually 6-mil polyethylene sheeting. Staple this to the studs and let it lap over the flange of the tub. You'll want the face of the durock to at least be flush to the face of the flange. Having the cement board slightly proud of the face of the flange is okay, too. If the cement board will not satisfy this as things are now, then use thin 1/2" furring strips nailed off on the faces of each stud to bring the framing closer to the flange. If furring, your poly would go over the furring strips. The cement board can be held just above the tub's flange. That way your bottom course of tile will cover the flange and stop about a grout width off of the tub. That tile/tub gap will later be caulked. Ignore the reference to "kerdi" in the following drawings. The two following sketches show tub sidewall details both with and without furring strips. In your case, you'd want the poly between the cement board and the framing.

Cultured marble or Swanstone solid surface (expensive) tub walls. Really, tile surround for tub is one of the easiest DIY. It is also one of the most affordable tile jobs to hire out. Alternative Sterling Bath/Shower 18 high, 58 gal, 13 1/8 depth. Here is a link that might be useful: Sterling Accord Bath/Shower