Which marker. Piranha does not make a pump gun i believe.
$50
There are no "a" or "b" buttons for paintball guns.
There are some companies that made after marker parts for the Piranha, though they would be a very tough find at this day and age.
No. Piranha makes cheap, but unreliable markers in the low to mid range markets.
Yes, many dealers have upgrades in stock. Check ActionVillage.com
DLX, the makers of the LUXE.
Brass Eagle, anything from walmart, and spyders,
Not really. For the price there are several better markers. The quality of piranha markers is not as good as say Azodin or even Tippmann. The marker has very poor ergonomics and is 30 dollars overpriced for what your are getting.
The purpose of a paintball gun is to fire paintball pellets, to mark opponents in the game of paintball.
A paintball marker is a paintball gun. It is just called a marker instead of a gun.
A 12oz tank will not last long on any gun. Most likely, you may get 400. 500 if the dwell is low.