Ok, so i've decided for real to actually try out linux and start learning about it.

I bought a book to teach me about it, but my particular case isn't in the installation section. See, i'm planning on putting Linux (either ubuntu or fedora, not sure which. hell if i understand GRUB right, it can be both) onto my portable flash drive (formatted as NTFS). What i need to know, is
A) can i install them to seperate partitions on the drive, even if it's NTFS,
B) can i then place data accessable to both linux and windows (my main laptop hard drive will remain vista), and
C) if i enable GRUB, will the computer default to the windows bootloader whenever the USB drive isn't connected?

i plan to set my BIOS boot order to (primary) USB/connected external drive, and (secondary) c: (tertiary) CD drive.