1) Is it common for every other person to have that 'I'm a mysterious guy who likes dark things' background? Noticed that on my hobbit (who is the complete opposite, really).
That is common, because to the players, many of whom are very young (under 30 years of age), it's "cool". If you look hard enough, you find people who aren't Lord Darkity Dark of Shadows.
2) Why are there so many elves in the Prancing Pony?
You find most of the non-lore elves in the Pony, because it's Landroval's only true RP hub. There have been several attempts at making an elf hub in Rivendell, and even trying for some hubs in Trestlebridge, Ost Guruth and Stangard, but players lose patience and just spring back to the Pony.
3) Is there anywhere else to RP other than the Prancing Pony? I mean, once I RP-ed briefly with a guy in the Comb and Wattle, but the PP seems to be where it's at.
The is RP all over the place on Landroval. Random RP (where it's not scheduled or known ahead of time via an event) is extremely rare to get on the landscape, although it's quite rewarding. I've had other RPers run across my RP in Tinnudir, Nen Harn, Mirkwood, Moria, etc. The Prancing Pony, though, is the one place that you're guaranteed to find it at most hours of the day or night.
4) RP-ing an old philosopher guy from Bree-land seems fun, but the total introvertness of his character seems to be a barrier blocking me from actually communicating with people. Tips, anyone?
You need what I call an "RP Hook". Just something that would either attract other players to you and give their character the IC reason to engage you or vice versa. One example I can give is one of my characters wears and ugly red and white striped shirt. Other characters come over and say "Boy that shirt is bright. Why do you wear it?" Perhaps your old philosopher guy could talk to himself? You could alter what he's talking to himself about (while reading something, perhaps) by who else is in the area at the time. Like, if there's a Hobbit around, be reading and then say "... hmm.. was it third breakfast next? Or tea? Or lunch?"
5) Is it common for people to go into the Pony and immediately know everyone that's there, but completely ignore the newbie RP-er in the area? Happens to me a lot.
Nope, that's only common with the most played characters. I've been on Landroval since the launch time and any time I make a new character, it has to be eased into RP, as well. Took something like 3 months for the last one I made to get known. Just have patience and keep at it, and watch for the ring of RP opportunity to strike.
6) Why are there so many elves in the Prancing Pony? Did I already ask that?
7) How exactly do I start roleplaying, rather than just dabbling in it like I do now? Just 'jump right in' or whatever, or will most people act hostile?
Aaand that's it for now. All that I can think of at the moment.
Don't jump right in unless it's something that you'd jump right into IRL. Like, if you have a Rohirric character and there's a table of Eored all speaking Rohirric, it's fine to walk up and say "Westu hal! I can't believe it, so many of my countrymen here!" or something of the sort. RP Hooks can be rough to get the hang of, at first. Above all, be patient. Also, it's fully fine to send an OOC /tell to someone you'd like to RP with but can't figure out how to do so and see if they'd like to help and what it would take for the 2 characters to notice each other and speak.
Favorite Dev Quote from 2009: Graal: The lack of an instant threat catch up skill is one of the differences in tanking between Wardens and Guardians, just like Wardens dont have a easily used forced taunt. It is unlikely, but not impossible that this will change. Bottom line...Dont die.