Sometimes. The firing pin and extractor may leave marks on an ejected shell that can be matched to a gun.
Sometimes yes, but not always.
There is a part almost all guns called the extractor that, like its name implies, extracts the shell when the bolt of the gun recoils back.
Depending on what you mean by "trace", the answer could be yes or no.
a firearm is a gun that fires bullets they're normally all have firing pins which hit the back of the shell causing a spark in the shell which ignites the gun powder and sends the bullet shooting of at over the speed of sounds.
can you use any kind of an 22 shell like an long or short shell in an 22 gun
Shell-ejecting airsoft guns tend to eject their shells using a spring loaded system. once the bolt, or slide is drawn back after firing, the spring will force the spent shell out of the gun
Impossible to answer without knowing the type of gun.
Yes.
Take it to a gun smith
When the gun is fired the shell casing is ejected by the blow-back gas and the next bullet is automatically loaded. All in one motion. The next bullet is now ready to fire.
What size shell in legnth are you asking about?
See a gunsmith.