The most common ones are found on merchants:
Shiskabab: Traveling trader or Vance in the Blood Ties quest
Railway Rifle: The merchant in Underworld or for bringing back the constitution to the Capitol Preservation Society.
Nuka Grenade: You get this for bring Nuka Cola Quantum to Siarra in Girdershade or for purchasing it off of Doc. Hoff, the traveling merchant.
These are only 3 of the 5 custom weapons in fallout 3.
no
You have to find the schematics to make it.
Yes.
you can make them with the schematics, you get it after completing the nukacola challenge, I'm not sure about the other schematics for it though
By it's self not much. But if you get the Schematics for the Railway Rifle it is a key component into building the weapon.
Yes. Just like in Fallout 3, you can find many scattered. Try bartering a lot as you may find them in small trade stops or on caravans.
You can buy the parts and the schematics to the rock-it-launcher from moira in craterside supply in megaton. Type your answer here...
electronic schematics help you know where to place and connect all the pieces
Go to www.hmaservice.com, register and all the cars schematics are there free and a whole lot more
i cannot answer all of this but Fallout wiki can! search Fallout wiki on Google... all your fallout needs plus lots of nuka cola, mmm im going there now...
Purchase the Haynes Manual for the Lumina, it has all required schematics.
Fallout New Vegas is all one game.