1. You can download Dashlaunch from here (you can't miss it) if you're using FSD you don't really need Xexmenu
2. As far as I know DLC don't work from external drives but XBLA does.
3. FSD does take up some disc space. It will include all your box covers, etc.
4. Don't know how you managed that but it should not be a problem
5. In NXE settings you can block Live accounts from being created and block the console from connecting to Live. You don't want to update that "something"... If you've block it in the settings you should be OK.
6. Yes that's to block the console connecting to Live but you can also do it in the NXE settings (just to be sure)
7. RGH is the hack that enable you to run dashlaunch, freeboot, etc. (RGH = Jtag) I've never used Freeboot so I don't really know anything about. You can always Google it and read up on it.
8. Depends when you downloaded it but it most likely is the latest. You can set FSD to notify you of updates. If an update is available you'll get a pop-up when you boot your console.
9. You can do that but you'll have to set your game paths again (and probably download the box art, etc again). Mine is set to notify me of an update and when it's available I just install it (via FSD).
10. Yes that's fine keep your saves on the internal for now. I suggest you get a USB stick, format it with the console in NXE settings and use that for your game saves.