You’re going to be an individual among a bunch of teams. And there may be others like yourself in there. Don’t try to form an alliance with a team, because they’re just going to try to use you for pack fodder. You’d just be playing a role in helping one of them win or place.
As for contact – if someone is creepin on you, do NOT take your hands from the bars. You shouldn’t even be in a position that some one can come over on your wheel. Four safe positions relative to another rider, and only four: Directly in front, directly behind, elbow-to-elbow, and elbow-to-hip. Anything else is risking a crash. Keep the elbows loose so that “incidental” contact doesn’t trranslate into your front wheel, let them act like “cat’s whiskers”, and that contact will serve as the notice to the other rider. A lot of Cat 4/5 riders will panic and tighten up when this contact happens. Don’t let that be you.
I could go into a lot on tactics… But it would be voluminous. I can just give you some pointers on when you might be able to take a flyer. As a triathlete, I’m guessing that you’ve got some TT ability, and maybe strong climbing, and maybe like a lot of triathletes you suck at sprinting (that was me in spades).
Cat 4/5 races tend to be pretty twitchy – no one gets away. When I was racing cat 4 (before there WAS a Cat 5), I could get some good solos by picking my moments. Just after a prime sprint, when every one is settling down is a good time. Go with the guys gunning for the prime, but go at 90%. Draft them. And when they sit up gasping after the line, keep going.
After those first frenetic laps when the pace settles a bit, you can try one flyer.
At any time you try to go, wait a bit and take a QUICK glance behind you (coming out of a corner is a good time to do this, and you want this quick so that you don’t look desperate). If you’re just stringing the pack along, swing close out of the corner and let a few riders by and get back in line.
It’s going to be a shock. Road racing and crits are very different. Use your first few to learn. It’s a rush and a ton of fun, and WILL improve your bike speed.