Your first question:
Control Panel > Automatic Updates > Then either choose "Download updates for me, but let me choose when to install them" or "Notify me, but don't automatically download or install them."
Second:
Every so often I just go into Registry editor (start > run > regedit) and go to File > Export. But I'm sure tehre's a program out there somehwere where you can automatically make back-ups (not sure on this one, though).