Not sure if this is just random generation or not...but what's up with some of my outposts having 2 shields and some having only 1? I understand that some specialists can do this, but these are specialist-less outposts.

Yes, it's just random generation. Some bases have weak shields(10) and some have strong shields(20). I know there is a wiki article that talks about map generation if you want to see the specifics of it.