@freeridr05 The USA Cycling website is a great resource for finding cycling teams in your area. From perusing their website, you can get links to the club websites and explore them. Unless the club is a race-only team where you have to have proven results to join, most clubs have group rides that are open to the public. [note: the websites usually have descriptions of the rides so you can assess what ride(s) might be appropriate for you to try]. So the best way to get a sense of whether you like the people and race team members is to go ride with them.
Depending on where you live (i.e. the density of clubs with race teams), you could try two or three such clubs. You don’t have to join a club with a race team to race. All you need is a USAC racing license (~$70/year). However, the advantage of joining a club with a strong race team is skills development. Our club, for example, gets most of its new members, both for the club overall and for the race team, after new comers have ridden on our group rides a few times and get to know the members/racers.
As to your question about team performance, that is available on the USAC site, both on the individual level as well as at the team level.
As for sponsors, that should be of little concern initially because you will be required to start at Cat 5 unless you have some elite non-sanction performance where you can demonstrate to the USAC governing body your racing performance is beyond the Cat 5 level (this happens when folks have raced in Europe and come to the U.S. to race). If you get through Cat 5 (10 races required) and you are an elite racer (several podium finishes), that will be a good time to evaluate whether can make the cut of an elite race team and begin basing your decision on sponsorship. However, until you get to Cat 1 and are at a pro-continental rider, most clubs seem to have the same race-reimbursement policies, so there is usually a long time before sponsorship really matters.