Mods for Fallout: New Vegas are installed by extracting all the files from the downloaded archive into your New Vegas data folder (which is the same folder where FalloutNV.esm is located) and then enabling the plugin (.ESP or .ESM) either in your mod manager of choice, or under “Data Files” in the launcher that runs when you start up the game.
The console can be accessed at any time during gameplay by pressing the tilde (~) key. By default, accessing the console will disable achievements for that session.
The Mod Index is a two-character hexadecimal string, with a value between 00 and FF, that you will sometimes need to find in order to use console commands. It can be found using a mod manager, usually listed somewhere beside the name of the plugin.
The Mod Index identifies a mod's placement within your load order and is also used to look up records contained within the mod's plugin. For example, FalloutNV.esm has a Mod Index of 00, so all records contained within will have a 00 prefix. The Mod Index makes up the first two characters of a record's FormID. Since the Mod Index will vary from player to player, this wiki uses double hashes (##) to stand in for the Mod Index whenever it's needed.
The FormID is a unique eight-character hexadecimal string that uniquely identifies each record contained in a mod's plugin. It's what allows the game to look up each record and use it correctly during gameplay. For example, the FormID for a bottlecap is 0000000F. The first two zeroes (the Mod Index) identify it as being contained inside FalloutNV.esm, and the remaining six characters are unique to that item.