Hi John, welcome along. In answer to your questions,
CCs are a good way of getting to know like minded souls in the game, there are country clubs aimed at particular nationalities, tier levels and whatever type of game play you prefer. You may not find the right one first time but give it time and I'm sure you'll be able to find a club right for you.
Unfortunately, you cannot be a member of more than one club , that said if you find the right club, you wouldn't want to be.
If you look at some of the threads in the country club corner, you'll find many willing to accept new members, take a look at the membership list of these clubs and see how many players there are at your level.
Most clubs have basic rules about posting, ie no abusive or discriminatory posts. Also a lot of clubs ask that you participate in club tournaments.