Mainly from the markings on the gun by the maker.
You can find information on how to make a gun online on Youtube and also at Wikihow. You can learn to make a 22 pistol and also you can even learn how to make a machine gun.
No
Find or become an Engineer and a Machinist.
buy one or find parts and build it
Yes
CZ does not make a gun by this name. Find a reputable gun shop and have them check what type of pistol you actually have.
You have to make one
I would find it difficult to find out what type of gun you have.
No. Even in jurisdictions which require registration of firearms, it is not made a matter of public record.
No, you can only craft, find or buy the dart gun in Fallout 3.
For most guns, a value is derived from what a gun of that make, model and condition is selling for. If you know the make, model and condition, you can check references such as the Gun Traders Guide or the Blue Book of Gun Values. You can also check on-line auction sites, such as Gunbroker, and look at COMPLETED sales of a comparable gun.
Can't be done with just the serial number.