Questions in topic: Clubs

To join the club you should find the one you like and then click Join club link in club listing. You'll be added there automatically. You can also join the club from the Club page itself.
Yes. You can do it in Clubs section-Create my club. When adding the club you can set it up to use Terms agreement before registration for the club, to be private or public, club description and icon, define club members permissions.
Yes. When you are at your club page, you can press a button Invite friends. You'll be transferred to your Hot list to invite your friends to your club.
You can search clubs by interests. On the main page you can check clubs categories and clubs in them. Location's indicated in club descriptions.
If you want to leave the club, just press Leave club link and you'll be unsubscribed from it.
Yes any time you can leave a comment for the club. You can also upload club photos and news for everyone to read.
When checking clubs listings, you can see how many people have joined and view their profiles by entering the club.