You cannot replace the trigger buy itself but you can buy a new trigger with new trigger frame like in the related links:
Yes you can get a regular or just an air expansion chamber. They are extremely cheap.
Air regulators, barrels, hoppers, asa, and trigger wells.
Tippmann 98, very durable and easy to fix.
Disassemble the gun, and replace the back cap with the stock or take it to a paintball store, and ask them to.
A paintball gun
You can purchase a Spyder Paintball gun directly from the Spyder Paintball website. There are also options for new or used Paintball guns on eBay. There is a wide variety to choose from.
.68 caliber. the paintball standard.
Tippmann 98's, spyder mr1/victor, and azodin ats/kaos are good to start.
as long as it is spyder threaded yes
Should take a standard type 45 degree frame that goes on the newer Spyder bodies. That being an electronic grip or mechanical.
Spyder MR100 Pro is the RIS Quad rail system that fits the Spyder MR1 paintball gun.
There is no "ak-47" paintball gun. there are many companies that make guns that are styled after the Kalashnikov series rifles. On the same note, Spyder makes several models of paintball guns, which vary from beginner "wallmart guns" to decent enough middle classed markers.