So much new information over the last few hours, and there seems already be conflicting information .. and the new information leads to many new questions; none of which could really be answered until the new gym system goes live (once a new app version is released and it is forced).
Based on the raid screenshot (sharing a home with the Nearby/Sightings list), it looks like one could potentially choose which raid you wish to battle in, based on the boss Pokemon that features. With the ability to capture the boss Pokemon after a battle, it hopefully means that you can go after rares, maybe regionals and maybe legendaries ..
From home I can see two additional gyms, and from work I can see three additional gyms.
When things go live again, the race will begin to be the first to claim the spot for my team and see how the new mechanics work.