As to where people are, sorry, didn't answer that before.
The game is old, and leveling is not something most people do the old fashioned way. Whether they are level 6 or 45, most people level by grouping with level 50 toons. This game rewards you in that and you can level much faster. Since most people already did the old fashioned grind, they don't have any interest in it, so they do it the quickest way possible (either Power Leveling, or just doing Level 50 task dungeons). The game begins at level 50, and people for the most part get there as quickly as possible.
For someone totally new though, I recommend you level in the battlegrounds. There are xp quests there that give great xp. YOu can get aurulite there to buy mediocre gear. The level 20-24 bg is a good place to turn off xp and earn realm points. Thidranki is somewhat popular, and you can see how RvR is there (not on PvE server though). Molvik is also a popular BG (35-39).
I've never played Gaheris, but I have done PvE on a regular server, and this game is nothing great when it comes to PvE b/c new content is not added regularly and it is stale. I would not recommend Gaheris unless that is what you are sure your playstyle will want.
Edited, Jul 28th 2011 10:21am by thuri