You're the Falls Church modern house, right? Well, there are about a dozen days per year, mostly in October, when having the doors open to the outside are possible without it being too hot and humid or too cold and humid. The whole area is a swamp after all. You might also find a few days in late March before the April rains come that are open door worthy, but if you aren't careful then, the wind will rip the doors right off of the hinges. Had that happen to a neighbor. There's no real good solution to screening out bugs for a 12' opening. At least none that are unobtrusive and really work for the giant bugs that VA has. And, no screen will keep out wildlife. There are more raccoons in an urban environment than there are in rural areas. They aren't at all shy either. And can open trash cans. And even some windows and doors. You haven't lived until you've chased off Rocky from inside your house for the third time that night! You learn to keep your doors SHUT and LATCHED.

The picture you posted to Photobucket is so tiny that the door details can't seen. Perhaps if you post a larger pic, someone will be able to help.

We have used Parrett Doors for exterior pocket doors. they are very pricey, but work great. They are installed in northeast in a very windy and snowy location and we have had no trouble with them whatsoever. The installation must be perfect as they are very heavy doors. I believe Rochester Doors in Rochester NY also make these doors. We did a clear 16' opening with 4 panels with 2 going each direction. You need a 24' plus rough opening to do this. They do not leak, but very $$$$.

Yea quite a question how to weatherproof a pocket door. Most likely why the GC recommends against it. Note the houzz inspiration pics are in san fran... you wouldnt find these in cold climates. The inspiration pics look nice but are they practical? Do they leak air or water? We dont know. Perhaps a large sweep meant for garage door bottoms. Wont look nice though. Maybe if they install it under the jamb? A real pain to maintain though. When they say they have a kit that works with exterior doors, I am guessing that means it will accept a door that used to be an exterior door, not that it is meant to be installed on an exterior wall. Implementing this idea will not be cheap that is for certain. An outswing door is more practical as others have mentioned. Perhaps a pocket screen door on the inside with the outswing door.