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.
Yes, many dealers have upgrades in stock. Check ActionVillage.com
No. Piranha makes cheap, but unreliable markers in the low to mid range markets.
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.
Which marker. Piranha does not make a pump gun i believe.
A 12oz tank will not last long on any gun. Most likely, you may get 400. 500 if the dwell is low.
$50
No, they are separate.
There are no "a" or "b" buttons for paintball guns.
It should have these firing modes Semi Automatic Turbo+ Full Automatic 3-Round Burst Response Rampage X-Mode
around 90 dollars.
Yes you can.
The Smart Parts Ion is a fantastic gun, in the sense it can be upgraded easily and it is not the most expensive gun. There are not nearly as many upgrades for the Piranha.