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...
Yes, The collectors edition comes with the game, a Vault Boy Bobblehead, a hardcover book of art from the game, and a making of fallout 3 dvd. all packed into a custom fallout 3 tin lunchbox.
no
it repairs your weapons
Yes.
You access console commands and then input the IDs of weapons this link can help explain all you can mod: http://falloutmods.wikia.com/wiki/Fallout_3_modding_FAQ
To the best of my knowledge you can't use the cameras in the game, but are mainly used to create custom weapons.
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.
All version of fallout 3 were censored.
The Pitt add-on in Fallout 3 offers a new main quest where the player has a choice to make which affects the outcome of the game and who your allies in The Pitt are. You will have access to new weapons, new unique weapons, new aid items and new side-quests. There are new enemies such as Trogs (similar to Feral Ghouls which crawl on all four limbs). If you purchase Fallout 3: Game Of The Year Addition, you will have all of the add-ons already included in the purchase.
Fallout New Vegas of course 5 examples:Scope, Plasma caster electrode, custom action, focus optic and 10mm recoil cap
The FatMan you are talking about is the MIRV. It's in the national guard depot, and to get in you will need to find all of the Kellar family chronicles.