Welcome to our forum.
It is great that you have done your homework and approached this whole poly thing from a smart frame of mind. You'll probably avoid many of the pitfalls as a result.
As far as how trustworthy the poly community is as a whole, I'd say my experience is that it's pretty trustworthy, at least 90%. But then, it just takes that bad 10% to ruin your day, so you are wise to be cautious. It partly depends on what sort of poly group you participate in. I think Polyamory.com is one of the more trustworthy sites out there.
I believe it is possible to find others to date and such, without coming out to your (conservative) friends and family. You just have to find a "second group of friends and chosen family" in the poly community.
There's a Dating & Friendships subforum
on this site that may help. Also offsite there's:
OKCupid and PolyMatchMaker are poly-friendly dating sites; the others are links to poly groups (and meet-ups) in your area. You can also try googling the name of your state or city with "polyamory" and see what turns up.
Hope some of this helps. Let us know if you have any questions.