If you mean can you fight your friends, yes you can, you need to enter an Arena, there are several to find, once in the Arena you can 'duel' with your friends.
No
In the fourth DLC at the end.
Yes but you have to wait some time before you can fight him again.
Assuming you have the 4th Borderlands DLC, the Interplanetary Ninja Claptrap is the final boss.
Borderlands traditions tend to be mixed. Please specify WHICH borderlands you are referring to.
the creator of borderlands is Gearbox
Borderlands 2 is out now.
borderlands
Borderlands 2 was released on September 18th, 2012.
No, Kreig is an add-on character for Borderlands 2.
Borderlands - novel - was created in 1990-06.
Borderlands - novel - has 423 pages.