Yes, I too have a huge respect for Joe, dating back decades. A lot of my experience comes not only from residential work, but from larger projects, especially institutional type projects (schools, hospitals, hotels, etc) In that realm, most work had flat roofs, ad anybody in the game will tell you they all leak. If you have convinced yourself that it's a good idea, and there is no turning back, see if you can find a contractor who does fiberglass roof/deck installations. I have talked to a builder on the coast who is plagued by flat rood/deck situations and the fact that they are in demand on beach homes. He claims that a properly installed fiberglass roof is the only thing that will have a chance of decades of performance. These things are done much like a boat with glass matt hand laid into a thick waterproof surface.
As for your deck rim concerns, if they are limited to the screen shot posted, I do not see an issue. There are virtually no second floor loads, since the wall above the rim is essentially a curtain wall running with the roof trusses. If you are looking to create a rim that's flush with the plane of the wall framing, for a deck that is a few inches lower than the second floor, inset a single laminate of LVL into the first floor framing. As for shear, the Simpson catalog will have everything you need. One final though, I assume that you are going with engineered lumber on the as much as possible? I would continue that out to the deck/roof assembly, as PT in this application will shrink ridiculous amounts, with a SYP treated 2x10 often losing 3/8 to 1/2" in total height once it reaches moisture equilibrium in a dried out structure. That kind of shrinkage can be a major factor in roof leaks, literally pulling flashing details and caulk joints apart. Good luck.
EDIT: Now you have me overthinking this too...LOL. The rim should be a lot simpler than I described, or whatever answer you are looking for from your CAD program. I would simply cut an LVL rim the length and width you need. Then install it with Ledger Lock hardened screws, hitting each stud and other framing member you can. Fastenmaster is the manufacturer and they will have all the load charts and ICC approval letters as required. If you do this, remember to offset your deck framing by 8' from the stud wall framing so that the joist hangers do not bury the Ledger Lock fasteners. Inspectors are no too fond of approving fastening that they cannot see.
