You can customize all the guns except the ones you pick up on missions.
if by standard guns you mean the silver ballers, then yes, they are one of the most customisable guns in the game allowing you to carry 2 instead of 1. add laser sights and silencers, extended mags etc.
You need a gunsmith
On battlefield three you can change about anything you want on your guns
I own this app on my iPod and unfortunately you can not customise your own guns
You don't.
No because a gun cannot be changed by a normal sibling or adult
Money
guns and blood
Lawyers Guns and Money - 2014 was released on: USA: 1 November 2014
guns
If you have enough money
guns and money