Q1. You can still install lilo or grub, just use the option to install it to your root / partition rather than the MBR.
Q2 You can install Linux anywhere (primary or logical) on the HD as long as there is room.
Q3. Not sure really what you're talking about. Linux needs a swap partition - usually twice the size of RAM - formatted as Linux swap. Windows doesn't use swap, it uses pagefile which does not require making an extra partition. Linux can read and write to FAT no probs and can read NTFS, but write to NTFS support is not good. Best to use FAT for this.
Q4 A single swap partition is fine
Q5 nvidia works for me, the recent driver packages from nvidia support all but the oldest of cards and if you do have an old card, you can still probably find support for it.
Q6 Don't really know, however, there's not much you can't solve using Linux, and if you do happen to have any probs with the MBR, you could always install lilo or grub to it and use either of these bootloaders. They're both REALLY easy to use.