Yes, all brand paintball guns use a tank or other source of pressure.
Not at all compared to actual paintball guns.
All guns can handle compressed air, but not all guns use co2. Check your owners manual for details.
The sizes 9 oz and all the way up to 20 oz can be used for paintball gun. Some of the paintball guns are supposed to be used by the larger tanks. So the size of tank depends on your paintball gun.
Almost all paintball guns fit standard 5, 9 or 20 oz tanks as well as air tanks.
Most paintball markers can hold a N2/Nitrogen/HPA/Air tank so I couldn't possibly list them all, if you submit specific markers I could tell you if they fired using Nitrogen.
sorry i do not know
All paintball guns, excluding high end guns, have a .685 bored barrel.
Yes they will all "fit" in that they will screw into the standard asa fitting. However not all guns are compatible with both CO2 and HPA. Check the manual before selecting a tanks.
Regular .68 caliber paintballs, all standard guns do. Also there is no "m16 paintball gun" , only guns that look like it.
.68. Almost all guns are this caliber.