Hello,
I'm rather new as well and I can tell you what I did to find reliable opponents.
First question: join a club, here the three that I'm aware:
We Band of Brothers
The Few Good Men
The Blitz
Good players, easy to find opponents, nice talk. Then they run tournaments, campaigns, and so on.
Second question: here you can find the last version of CMHelper.
Very useful program that keeps track of all your games (who is waiting, engine versions, etc.) and you can chat with your opponents.