Hunters can be pretty beast in PvP, but so can many other clans, like mages, dks, etc....it really depends on the player and how much practice you've had. Just look around, check forums, and you can find a buncha tips. ;)
I think this is both good and bad...good for those who are more casual, but bad for those who are a little more experienced and can get much further than level 20 within the trial period
I believe a lot of merchers lost money with this, although it was a pretty big risk from the start not knowing exactly what the update was going to be. ;/
I'd have to agree, summ tanks are quite cool and a true pain in the ass if your fighting them :P Although, I also like barrows pure (70 def) if that is technically a pure. They are quite balanced and pretty high level'd.
Your best bet would be Rock Crabs as they do not hit often, but there are a large number of them. You could also try Soul wars if that doesn't bore you too much :P
Good luck