I answer the questions as you posted them

Welcome to the family first of all.
1.) The actual barrel cannot be replaced.
2.) I may be able to make a phone call and get you a static breech, but you cannot buy one straight from W/M as they are no longer in business. I know there was a website posted on the forums somewhere that someone found an online store in Cali distributing A80 parts, though I was not aware of this dealer, they may still have parts.
3.) Tourney cap...same as above.
4.) There were many problems with the first generation breeches. They were often not calibrated thus all the chopping problems. You may have a jewel on your hands if it doesn't chop like crazy. This mostly occurs from the overpressuring of the barrel moving back, thus crushing the ball if it didn't slip into the barrel. I would suggest that if you could get your hands on the 2-stage bolt kit and the static breech, do it.
5.) Yes, your lifetime warrenty is still honored. If you do encounter a problem in which you feel like you need to send it into the shop, you can still send it to WarMachine (I suggest stongly that you call first) and we will work on it there. W/M still honors all their warrenties on their guns, they just ceased production and services.
6.) In this order, you should upgrade: the breech and 2-stage bolt, get a nice barrel (autococker/timmy/matrix threaded), regulator, overdrive chip. None of these are essential and if your gun is working right, don't mess

Now if you are going to upgrade to better play tournements and such, I would get the breech, a barrel, and the OD chip over anything first.
7.) If I have an extra SF/OD chip lying around, you can get one from me. If not, I can check with Chris and see if W/M still has any.
8.) For maintainence, read thru this entire thread...it'll do you good if you want to learn a bit more about these guns.
http://www.pbnation.com/showthread.p...hreadid=249422
9.) $168 is a pretty good deal seeing as they are starting price $180 on E-Bay and those are from Archon Paintball. If I can ask, who'd you buy it from?
If you have any trouble with the gun, just drop me a PM or post here and hopefully we'll be able to help ya out.
Happy shooting.