By Nitrogen I am taking it that you mean compressed air and as long as the tank is high pressure it should work fine.
No, it is slightly different shaped.
No, their e-grip setup is slightly different and will not fit. Also the Alpha black's egrip upgrade is 30 dollars less.
CO2 or HPA will work fine with it
You need to buy a separte attachment for the A-5 and you should check to see if it is able to support using nitrogen
Yes, the tippmann 98 and the tippmann custom are the same marker, therefore the threading of the barrel will be the same.
The 68 does not have a removable barrel.
The A5 Is the best out of these mentioned, even wi price considered. It is the same price as a alpha black (bravo one in canada) and a cyclone feed, but is easier to take apart, has more upgrades available, has a tombstone adapter instead of the plug or screw in vertical adapter. The X7 (non Phenom) is just the A5 with more plastic parts for more money. The Tippmann X7 Phenom is a superior marker to all other Tippman's because of its Spool valve and ability to work semi automatically without a battery and fully automatic with a battery.
yes my 98c flatline works fine on mt AB, but the flatline cover doesnt fit cuz of the carrying handle lol. you can also buy barrel adaptors for things loke spyder barrels, or dye. and i think smart parts works on all guns but im not sure about that one
The tippmann 98 egrip.
Everything except for cyclone feed hoppers.
No, it will not fit.
98Shooter: I wouldn't recommend anything from the US Army series. Some of Tippmann's less desirable work, though they look cool the distance isn't near other guns. My 98 Custom outdistances it 6/10. If you are looking for woodsball i wouldn't recommend it, and i don't play speedball so i couldn't tell you for that.