Can I use the airport if I'm sided with the institute?
Yes, but I found the place very awkward to build in, when I tried.
There are very very few spaces for food and water pumps (no standing water, so no water filters).
There are also a few concrete bollars you can't remove, which restrict your building.
Plus the size is very very small, and it's restricted by concrete walls, which have some holes in them, which you can't patch easily with the materials available.
I wouldn't recommend it as a settlement site, maybe just a personal house.
It's really only intended for one mission, where you have to build some large items, and can choose to do it with the Brotherhoods help.
Anyone find it a little bit jarring that your characters are given slightl background stories?
Mainly the fact that the Male Character is always a soldier (this I don't mind too much), and that the Female Character is always a Lawyer.
Meaning if you play as a female, your character in 2077 was an American lawyer, then the bombs dropped, and they were frozen, and they wake up in 2287, but to them it's been minutes since the bombs fell.
They get outside, and within days, or even hours, they're chopping limbs off, blasting people in the face, planting explosives on priests, etc, etc...
Doesn't quite mesh.
They were very good to not impose much story on your character, besides being a pre-war married parent, but that one thing for female characters can imply just a little bit too much about your character.