Dont get a flatline barrel, they are junk hand down. I had on on my old 98 custom and used it for one day of woodsball and hated every minute of it. Just get a nice two peice J&J barrell.
As far as woodsball go with a Tippman hands down, they are the Glock of the marker world. Your choice of which one you want is up to you so go with whats comfy. Go down to Columbus paintball and try them out they have everything you need.