no, like i said, i dont use them
1. Dwell i beleive is how long the gun releases air (or how long a valve stays open) after you pull the trigger. Thus less dwell = better air efficiency but if it gets too low the gun wont fire correctly.
2. High output, plus they work on more guns than low.
3. No, dont get a halo IMO. GO with a vlocity or vlocity Jr. I have a pulse and it works good too. The halos seem to be the most picky and finicky hopper out there, and the heaviest. Ive seen so many of them break and i hardly ever see any Vlocitys break (and i work at a field)
Sure, there are some great barrels in each price range:
CP classic barrel (IMO, best value barrel)
$50 - $80
1 back pepperstick
$80 - $130
Full freak kit
Deadly wind whisper (1 insert)(IMO, best barrel on the market)
Full deadly wind kit
I know i am probably forgetting some good barrels. These are just the ones that popped into my head right away. Any of these barrel will be good on any marker you use. Also i would suggest a 14", as the 16" feel a tad too long, but even if you got a 16" it shouldnt be too big of a deal, just dont go any higher or lower.