Hey man, I was in your position two years ago, just slower. I ran 4:52 / 10:31 in high school. I contacted the coach even though I knew it was a long shot, too long. He shot me down pretty quickly, but you're significantly quicker so you probably have a chance. I would say if you end up running like 4:35, you'll have a pretty decent shot.
Now, as far as the running club goes; they're are some great people in the club, but I can tell you it's not super competitive. Almost definitely a few notches below what you're experiencing in high school. People just sorta show up when they feel like it. There is usually a track workout every Wednesday, and the club attends probably four or so races each semester (a couple club xc meets (8k), a few local 5ks, and the Amherst 10 miler). They're are also plenty of other local races that you could attend on your own, trail races too if you're into that. I also believe they're a couple open indoor meets at Smith college nearby (flat track).
In terms of how fit people are, they usually run anywhere from 3-10 miles a day in the early evening, typically at 6:30-8 min pace. Most of them are running faster than they probably should be, but I guess that's because most only run 3-4 times a week. I think at the moment there are a couple sub 17 5k guys in the club and a bunch of 18-20min types, but don't quote me on that. Long story short, you'll have good company and conversation for your easy-medium effort days, but will probably want to do more stuff on your own.
I haven't been in over a year due to a knee injury that I'm just starting to recover from, so maybe things have changed a little, but probably not too much.