1. Some of the guns are airpowered and do not need springs, I would suggest bring the springs to Ace Hardware to compare to others.What kind of springs should i be using and for which gun
diameter?
Length?
Where can i get them ?
What about stretching springs how does that work?
2. Same as 1.
3. Well longer is better because you can always trim the spring to be shorter.
4. Ace Hardware or McMaster online.
5. You grab the two ends and stretch it until it is longer. It will temporalily make it stronger but it will weaken the spring in the long term.