Fah
The main menu scenes are stored in *.thn files, in the Data/Scripts/Intro directory, use the "Thn Decoder" (somewhere in dl's) to decode them.
Hiigaran
If you couldn't be bothered to look
at all I don't see why I should bother to write it out for you. Look in the downloads section for the "UTF editor", and extract the various textures under the "Texture Library" node. They're stored as either TGA files or DDS files. TGA files are easy to edit, but you'll need a plugin for apps like photoshop to open DDS files since they contain detail maps.
Draven
You need to open Data/Equipment/market_ships.ini, and find the entry for the base where the ship is sold, it should begin "base = XX00_00_base". If you don't know the base code just post up the name here.
Look at the lines underneath to find the Sabre XR, it should read "MarketGood = <shipname>, <level>, ...
Simply change the "level" value to something lower, save and restart FL.
Rala
Some pretty ambitious ideas
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Unfortunately you cannot have AI wingmen in MP, although you can set up patrol paths etc. to make it
seem as if they are attacking and retreating, and not just fighting.
Moveable stations is, well, almost possible. Not ones that players can fly, but the static stations can be made to move. There is an entry for planets that causes them to spin on their axis, you can use the same method for stations:
Create a copy of an existing battleship station model, but enlarge the model area and move the fulcrum a long way from the centre of the model. Then set the model to spin (Using "spin = " in the universe entry) and it should orbit the sun, or whatever is at the centre point.
For the XML file, read the info that comes with FLMM for how to add/remove/replace files.