1. How is the population of the game? Should I expect empty lowbie cities, and cap players afk'ing at the end-game zones?
yes, for the most part. however, alot of endgamers will also afk at the lower lvl cities, as they are the more central hubs as well.
2. How is the community attitude/maturity? I'd prefer not to run into the "I'm better than you in every way" type of person.
fairly decent i have found. get some good people to show u the ropes or just have fun with you, and you should be fine. the vast majority of the population, while they like to bicker amongst themselves, is usually very friendly/helpful. heck, even when they don't seem it, they prolly still will end up helping you out of boredom at the very least(don't worry about being bored though, most of us have been around for years, so we are kinda at the "been there, done that, waiting for new content or some noob to help" stage :P )
3. How is the balance between free/paying users? I don't expect complete balance, paying users certainly deserve a boost.
hehe...hot topic here. f2p takes a HUGE amount of time to compete with p2p. that being said, the entire game can be accessed by being f2p(no exclusive content, etc, unless i am forgetting 1-2 minor details).
however, since you stated you don't want to rush to endgame and enjoy ALL the content, f2p is very much viable, as most of the p2p stuff is for higher levels/endgame, except maybe a mount(which can be purchased ingame as well, not perm like IS mounts though, but ingame rentals are a good price). the rest can be obtained by either buying from other players(gifting) or from phirius tokens(daily quest rewards).
until you are trying for endgame quickly(or quicker than f2p would take), there really isn't a burning need to spend any money imo.
4. Does this game receive a lot of content updates/bug fixes? Does the game have good management?
errm... -no comment-