1) take the 4 gig card out. if you dont have a hdd then i would advise to install to big enough usb pen or external hdd and run from it re-install fsd 3 do another scan then try downloading updates.
2) i believe the downloads you get are the game picture,info & screen captures.
3) if youve taken the 4 gig card out your battlefield 3 with HD TEXTURES should be a god file and installed in content etc folder (only hd content needed).
Had the problem myself at one point the 4 gig card just causes problems, happy gaming