For any paintball markers that runs on batteries with electronics (excluding mechanical markers that can be fitted with electronic grips) it's recommended you use HPA tanks. Aluminum tanks are your best bet. However, if you have a bit of extra cash and a stickler for hauling that extra weight, then there's carbon fiber tanks. Just make sure you get them hydro-tested every few years or so to make sure it's still safe to use.
The brands I know are good are Crossfire and Ninja as I've used them before. Guerrilla Air isn't bad either.
Planet Eclipse Etek 3
At that price there is only the Proto 2011 and the dangerous powers FX. If you want a spool valve gun, go with the proto, but I believe the ETEK is the best choice.
At bare minimum: the Invert halo too. if you want a perfect fit: Empire prophecy. anything better then that is probably overkill.
No.
Where the air tank or co2 tank normally attaches
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.
yes
There is no paintball gun that runs on only 200 psi.
No paintball gun will work without a CO2 tank or other propellant tank. without Co2 there is nothing to push the ball out of the barrel.
A paintball gun, unlike airsoft or real firearms will have a hopper on top, and will have a co2 tank sticking out of the back.
There is no such thing as a "CA" tank.
This is a personal question but from a neutral standpoint yes. It has very good efficiency as well as a light build. The Etek 2 also has the possibility to be upgraded to resemble an Ego 08