1. You can't easily at the moment this isn't in the engine yet, however you can replace the files in "Files\titlesbank\default" as that is where they are all stored.
2. Approx 5GB isn't much at all for the amount of media that is included and that is with me having loads of store content and TGC packs, this isn't a game it is a game engine and comes with far more media than a built game would require, this will only grow. I doubt many people will have an issue with storage space. Modern games can come in at 30+ GB of data FPSCR isn't at that size yet
3. Not yet no, this is beta software so you cannot change this yet.
Windows 7 Pro, Intel i7 3.8 GHz, 16GB DDR3, NVIDIA GTX 780 4GB Superclocked