No.
Self defense, collecting, shooting.
No. You do need a permit to purchase, but no registration.
You need to visit the BATFE website. They have the answer to your question.
Federal law = 18 for long guns and 21 for handguns
You need to go to the CDC and FBI websites.
Check with your local police.
Yes, handguns have a serial number.
Yes, handguns were used in WWI, and WWII.
I doubt that there are 16 different TYPES of .45 caliber handguns made in the US. You will need to define your question a bit- revolver or auto pistol, which .45, and how YOU define "controllable".
You need to find a copy of Dieter Marschall's book on Walther handguns.
Virginia does not require licenses for ordinary firearms, including rifles, shotguns, and handguns.