Congrats!
I think it depends on your field what you where but I’ve always been told no ‘suit’ as in the matching kind. Trousers, nice top, none matching jacket (or none of truly boiling!).
Definitely plan to talk concisely about your research interests, how they link to the project, how you could further your interests via future collaborations (more grant money!).
Yes, I would definitely read up on any interview panel members and prep questions for them about their work as it fits your interests/the project.
Also, I think what really helps is presenting yourself to be a team player, easygoing, someone they’d want to work with, present yourself as someone keen to get involved in the department (committee work, teaching, etc). Obviously not in an insincere way but I think they like to see that you want to be involved.
And I wouldn’t stress about the second interview. Their loss! My feeling is always if you value what I have to offer enough, you’ll make time for me. If not, it’s not the right fit.
My current senior postdoc position I got offered an interview right before xmas on a week’s notice. It required travel. It just wasn’t possible with school holidays for me to be available then on such short notice 3 hours from home. I explained this to them. They couldn’t get the interview panel together again until about 3-4 weeks later so they really scheduled me for then. They called me the day after my interview to offer me the job. I was obviously the preferred candidate and they were happy to bend over backwards to find me a suitable time. If it’s the right fit, they’ll be keen. If not, I’d let it go and focus on the other one.
Good luck!