Roof is around 1300 sq feet and I need to replace current membrane. 

It could be an easy fix like painting the walls with a waterproofing membrane, or it could require a more serious foundation repair.

The higher bids include creating a slight slope using varying thicknesses of insulation under the membrane.We've encountered a few different options in the quotes:Reinforced EPDM vs. 60 mil membrane: One roofer suggested reinforced EPDM for superior puncture resistance, while others argue that upgrading from a 45 mil to a 60 mil membrane is sufficient for occasional foot traffic (for inspections), falling debris, and hail.Attachment methods: Some roofers propose mechanical attachment (especially for reinforced EPDM), while others prefer an adhesive method.We're seeking advice from anyone with experience in EPDM roof installations.

If we budget waterproofing (membrane) for the crawlspace and accept that the treatment was done (with a bond) and the repairs completed (photos provided), what would your thoughts be on proceeding with the purchase? 

Consider adding a sump pump or waterproof membrane if needed.2.

.- Additional subfloor (wood) and cement board (floor) $100- Shower cement board $75- Waterproofing Membrane (I like to do this) $150- Shower wall tile (80-90 SF) $150- Flooring tile (30-40 SF) $100- Tile setting and grout $75- Vanity with top and mirror (24" it looks) $250- Toilet, wax ring and feed line $100- Faucet, feed lines and trap $75- Trim $25- Accessories $40- Fan/light $150- Vanity Light $50- *Shower diverter valve with trim kit and plumber to install and help set tub/drain. $750- Screws, adhesives and fasteners (cement board screws, caulk, etc) $50- Paint $40- Miscellaneous $100TOTAL: $2530With all of that said these numbers would be my BASE run, and assuming I was spending my budget amount on each item.

My installations on plywood or OSB subfloors are on HardieBacker and waterproofed with paintable membranes -- I built the tile floors in my rentals like shower stalls walls.

Then installing plywood back over the framing, new waterproof membrane, and new siding on the outside of the house.  

If you still hear them too much, a laminate floor up there floated over an acoustic pad/membrane may further separate the surfaces transferring sound.

After installing the cement boards and taping them and all that jazz I ended up using a waterproofing membrane which was considered optional.