Well, I have learned never to bring up disability until the job is offered. It's very hard to prove discrimination otherwise. Even if you're dead sure that's what it was. But, yeah, my UCSF friend said I should just mention it when I'm at HR filling in forms and getting oriented. If that should come to pass.
Underpaid can be relative. I've been underpaid almost all of my adult life and grossly underpaid in my last job. The lowest end of what a PA1 position pays is already about 5k more than I was making. But when they asked me what salary I was hoping for, I went 3k above what I'm shooting for, to allow some room for me to negotiate me down, if that's what they want/need to do. I felt very nervous asking for that because I'm not the most assertive thing in the world. But whereas I took my last job thinking that while I was starting low I'd soon prove my worth to them and earn raises, I soon found out how wrong I was. So better to start at what you really want because there may not be any raises coming.
The department culture sounds great, though. That's the biggest job attractor for me.