Re: Getting in a band with older musicians
Take the gig. That happened to me, and I learned a lot from it. I was 20, the next closest was 28, then 31 and 36. Listen, play, get understanding of the band and how it operates...all that stuff.
There's a chance that some of your bandmembers have gone through some things musically that you might not have to...things that they've been burned on and know to avoid. Learning stuff like that can be valuable. It also gives you an opportunity to see someone leading a band [since it likely won't be you, the youngest and newest member] and how their decisions affect the group.
You're younger, so prepare to hear that a lot. Build a skin so it doesn't bother you. Forge ahead with what you're doing [learning musical life experiences] and let the other guys do what they're doing. At time goes by your opinions will hold more weight. It'll require a serious amount of team player focus for them to accept you into it, but that's a good challenge in and of itself.
I would take the gig.