2. Are you sure it is "vista" you are seeing or the Windows 7 bootloader? (try clicking into it to find out)
3. No, you can not delete Grub by just hitting F7 at boot.
4. Backtrack is not a program, you can not "Uninstall" it. You can delete it, but thats more basic linux/partition problems, not a BT related issue.
5. You can edit the booting order by changing the Grub install. Google "boot order grub" and you will find your answer.
Hope this helps. Respond if it doesn't.