I don't see why dual-booting would screw it up. Just don't install Windows after any Linux installations as Windows tends to overwrite the MBRs. Always install Windows first. I've myself dealt with 7-way multiboot installations and as long as one knows what one is doing that and much more is doable without harm. A simple dual boot with Windows and some Linux distribution is trivial as long as one installs Windows first and lets the Linux distro take responsibility of the boot loader.
Debian has the root account enabled, no need with that sudo stuff, just su to get root when you need to.
You can choose what you want, just don't select the "Desktop Environment" option during the second phase of the installation. If you select that you'll get the Gnome desktop environment + lotsa stuff. So don't select that if you don't want that, and instead pick and choose more finegrainedly, either with straight apt or with some frontend, e.g. aptitude or synaptic.
GCC is typically installed out of the box, but if it isn't due to some very mean and lean installation approach, just install it through apt.
Same goes for GIMP, Gaim and OpenOffice.org - just install them as you need them, they are just a simple apt-get install away...
The
netinstall image is typically the best way to go. You'll get the same thing installed, the difference is just that you download only what you want/select when using the netinstall.
The full CD and DVD sets have their place too, but mostly for situations requiring installation with no Internet access available, and of those the two DVDs are much more preferrable over the fourteen CDs - which is quite an annoying disc juggling operation. And only the first disk of the CD/DVD sets are required, the contents are ordered so that the lower the disk number the more commonly required things are on them. But the netinstall image is typically the best way to go.
