Also, don't forget that at level 17 he'll get access to Retainers and some much needed storage space. And by the way OP, when we mention levels like this, it's never about your character level but rather the Main Quest level that the reward comes from. Just play the game for a while, all should be made clear through the pop-ups that explain pretty much everything. And for the rest, ask around in game or here.

As for servers, Exodus is a prime example of a heavily populated server while Malboro is at the opposite end of the spectrum and is lightly populated. Each have their own advantages. High pop server = never gonna be alone but makes it easy to find people to party up with. Low pop server = peace of mind and the ability to solo some world content during the off hours (at 5am, there's nobody playing). If you intend to do some gathering, then i'd recommend a place less populated as it's very annoying to have 3 to 8 people all exploiting the same nodes. I used to be on Exodus and this happenened all the time, then switched to Malboro when it became possible to switch (RL friends there) and now even in the prime hours, I rarely have more than one other person gathering at my spot.

With that said, both high and low pop servers will have Free Companies (guilds) you can join, some small and some huge. Getting into a community is not hard if you are social and not a jerk. If you want a really big one, head on over to your server's forum here and check them out. If you want a smaller one, then make some friends in the game (or on these boards) and you'll get tons of invites.