u dont
No
There are several types of guns on Borderlands 2.Here is a list, Pistols, Sub-machine guns, Shotguns, Assault Rifles, Sniper Rifles ans Rocket Launchers.Each type of weapon has thousands of models, they get better as the game progresses.
Specificly ones compatible after patch 1.30
billions because they are randomly generated with different stats
It's full of guns, gore, violence, murder and swearing.
They work on, repair and modify guns and rifles
There are vending machines at certain places where you can sell any unwanted loot and buy new weapons.
No
No because a gun cannot be changed by a normal sibling or adult
Borderlands is a game with infinite possibilities there is no telling what you will find but trust me you will soon get sick of alien guns if you get the secret armory their not that good, and whats stag valley? I think you mean skag gulley.
They repair guns. They may also clean guns, add accessories such as scopes, or modify guns to correct poor triggers, smooth actions, bed stocks to improve accuracy, etc. Some gunsmiths may manufacture guns.