I am wasting materials by getting PT Plywood but it is cheaper (not too worried about material cost in this situation, more for a better outcome).However, he stated we needed to avoid the "gap" so water doesn't permeate through the bottom level. 

If you have enough water permeating the tiled walls to actually run down the wall to the pan, you have bigger problems than what a coating or vapor barrier could address.With full contact of thinset, there shouldnt be enough connecting voids for water to pass.

Furthermore, marijuana has a very prominent and distinct oder which will permeate the house and can be rather difficult to remove.

I'm thinking about Imbue Property Management (Imbue: to inspire or permeate with a feeling or quality).

If you don't have forced air circulating in the space, then put a space heater below the window.If the mold has permeated through the drywall, and is not just on a surface that can be cleaned, then you may need to replace the drywall.Check with your local utility company to see if they offer free energy audits.

Is it possible to remove the smell if it has permeated the structure?

My only guess is that the water might be permeating the concrete block wall.

The odor permeates into all of the rooms in my apt making relaxing and sleeping somewhat difficult.

If I did go that rout I'd have to put permeate financing on it as soon as I completed my rehab @Billy Mclachlan I actually have sent her a hand written letter but I do like the way you think.

The principal differences being:the electric baseboards (EBB) are install and controlled on a room-by-room basis; andEBBs rely on convection to permeate heat into the room (there is no fan circulating the air)In theory EBBs should have similar operating costs to a centralized electric forced air furnace (if not lower), however, in practice, that is usually not the case.Because of their reliance on convection, EBBs have slow recovery - i.e. if there has been a draft (someone opening an external door or window) or if the heat has been set back during the day and was turned up on the occupants return.