Monk with harmony and psychometabolism is the route I'd go for ease of pve (so Celest or Serenwilde). So many great buffs/defenses, I'm usually a bit jealous of Harmony. For pve, you really only need two monk attacks (forms). One that is just hand attack/hand attack/kick, and one that is raze/hand attack/kick. The advantage of monk as well is you have three hits per attack. If I remember correctly (I haven't done any actual killing pve stuff with monk attacks) each hit can be a critical hit. I like that since without damage shift (a fairly high investment skill) you can "waste" a lot of damage with single, large hits.
For race, I'd say it really comes down to the demigod powers, most prior to that are meh with exception of humans who get +20% xp (but humans are stinky). Orclach and loboshigaru are great from a survivability point of view. Taurian, dracnari, and viscanti are great from a mostly offense view (though drac and visc require a 1k credit artifact to unlock the ability) as they gain an extra attack against your target.
Hope this helps some. And if I'm spreading misinformation, someone please let me know.
1. Monk is wonderful for PVE if we're talking directly out of the box, given the utility/buffs that come with certain skillchoices (Psionics - Psychometabolism) along with attack speed and damage. Any class can access "peak performance" bashing with the availability of gnomeweapons, though these do require a particular skill and gold investment or helping hand to get early on. Not a necessity, just a nicety. Warriors can also likely be competitive for vanilla bashing, and are slightly more approachable IMO. Can't speak much to the specifics of classes v. archetypes as I've only recently played with Gaudiguch's, and haven't bashed without a gnomeweapon for a while.
2. Population is currently highest in Magnagora, Gaudiguch and Celest I believe, not necessarily in that order. Celest is definitely the one you want for good-leaning, Magnagora is edgy-dark, and Gaudiguch is largely ambivalent with very subtle, morally-questionable undertones. It's fairly likely you'll find pretentious RP lurking in any org, but it's definitely not something I've experienced on the regular. Helpful people exist all around, and even if someone isn't immediately awake in your org, the newbie channel won't let you down for Q&As.
3. That's a really wide net to throw out! The initial introduction and city/commune collegiums beyond will cover a lot of the basics, but there's always something new to learn, so it largely depends on what your interests end up being. The best advice I can offer is to first try the in-game HELP system, as that's going to be the most up to date thing there is. Of course it doesn't cover everything, so pester pester pester - most folks are more than willing to answer as many questions as they can, or at the very least refer you to someone who can help more. I like to think we have an awesome community in that regard. Also, Discord! There's a general server for the game at large that a lot of people frequent, and your org likely has its own server as well. I know Gaudiguch's at least is wonderfully active, can't speak for any others though.
Please people. Its hard enough to keep people motivated to participate in stuff. There's no need for your snide remarks or commentary. It's sad and unneeded and frankly, some days, infuriating. If you're defeated, accept it with some dignity as having been bested. If you win, wear it with a smile. We play this game together, lets keep that in mind, hmm?