Wherever you need to. If you're in a field environment, just don't take out the firing pin or extractor, for the sake of not wanting to lose that tiny extractor pin or the small cotter pin which holds the firing pin in place.
If you look at the bolt face, a center fire rifle will have the firing pin located in the center of the bolt. A rimfire rifle will have the firing pin located on the outside edge of the bolt.
For which firearm?
If the firing pin is in the center of the bolt it is center-fire. If the firing pin is at the edge of the bolt it is rimfire. The base of a center-fire cartridge will have a small circle in the middle made of different metal than the case. The base of a rimfire cartrige will be flat, maybe with a trademark engraved on it.
The bolt carrier, the firing pin, the carrier pin, the extractor, the cam pin, the bolt, the extractor retaining pin.... that's the assembly, but the charging handle is also defined as part of the bolt carrier group.
firing pin , breech block, and extractor and ejector mechanism
Trigger with trigger bar, trigger spring, connector, trigger housing with ejector, locking block, slide stop, magazine catch, magazine catch spring, slide lock, slide lock spring, locking block pin, trigger pin, trigger housing pin, Frame, Magazine tube, magazine floor plate, magazine spring, magazine insert, magazine follower, front sight, extractor, rear sight, firing pin channel liner, extractor depressor plunger, extractor depressor plunger spring, Spring loaded bearing, spring cups (2), Firing pin spring, firing pin, firing pin spacer sleeve, slide cover plate, firing pin safety spring, firing pin safety, barrel, recoil spring assembly, 36 parts unless I missed one.
When the striker or firing pin connects with the rim (on a rimfire) or the primer (on a centerfire), and the cartridge does not fire.
Rings, extractor/ejector, firing pin. forearm
Bolt and bolt carrier group
In general, no. The cartridges will have differing shapes and sizes, a a rim fire firing pin strikes the rear edge of the cartridge, where a center fire firing pin strikes the center of the rear of the cartridge. HOWEVER, in past years a very few firearms have been made with a changable firing pin that could fire rimfire OR centerfire ammuntion of the same caliber.
Sometimes. The firing pin and extractor may leave marks on an ejected shell that can be matched to a gun.