I started playing a little while ago as well. So far from what I've seen, bots (other than spam bots) are extremely rare on the PvP server. Probably because they'd just get PK'd over and over and couldn't do much, so not sure about PvE servers. I haven't seen any or heard any complaints of any big hacks or exploits either. Not sure what you mean by easily accessible servers, but there's no queue time or anything from what I've seen.
The game is called a WoW clone for fairly good reason, the UI, controls, a lot of it is reminiscent of WoW. That's part of the reason I enjoy it, after being rather disgusted with the last two expansions, I just wanted something different. The gameplay is intuitive since its similar, but different enough that its a totally new feeling, and with many other good points. You know all those things you might say like, "Oh I wish XXXX was here," when you play other games? Chances are its in RoM, since its basically designed from good points of many different successful games. The game is still new, they are raising the level cap and adding new races and stuff soon, but its definitely one of the best F2P MMOs out there.
As for which server most jspers are on, I haven't the slightest. I play on Grimdal though
Its the only PvP server atm.