A proto slg can use CO2 or HPA. I contacted DYE tech support because their website says it can, but the manual says no. Their reply was "All SLG's are able to be used on CO2. Only being able to use High Pressure Air is a misprint in the manual. It might have been copy and pasted from our other manuals. Since all of our other markers cannot use CO2." So, yes, you can use CO2
You should use HPA with a Proto SLG.
Proto SLG all the way. Stay away from the spyders.
Yes.
.693
9 volt.
The threads are autococker threads. All proto and dye guns have autococker threads.
Yes, as long as it is Auto-cocker threaded, any barrel will fit.
Sadly no. The Ultralight board will only work on the Ultralight frame. If you are looking for a good board though, maybe look into virtue boards.
Although both is decent for the price, the SLG is better. If you have money for the SLG, go for it, otherwise the Piranha GTI is good enough.
yes, also has a couple other modes
2 lbs. 2 oz
No CO2 is required in order for a toilet to operate. They work just fine without it.