By configuring the bootloader to use Windows as the default menu option instead of Linux. Refer to documentation on how to do this.
"Mode?" They're two separate operating systems. If you're in a dual-boot, you simply reboot and select Windows instead of Linux from the boot menu.
You can. But the Windows installation does not put an entry into it's boot menu, so you have to manually copy a boot sector, and modify the boot menu so you can boot Linux. Linux distributions expect that you may want to dual-boot, so they detect Windows and set up an option for it automatically. For convenience's sake, it is far easier to install Windows first.
Yes you can. Ubuntu's WUBI uses the Windows bootloader (NTLDR) to boot Linux. It also uses the Windows filesystem (NTFS). This, however, is not the traditional way to do things. The traditional way to dual-boot Linux and Windows is to use a generic bootloader such as Grub to boot both Windows and Linux.
I suggest installing Windows, and then Linux (preferably on different physical hard drives). When Windows is installed it tends to overwrite the boot partition, making it difficult to boot linux afterwards.
Yes.
Get Linux!
Yes.
If you have a USB drive and your BIOS supports booting from a USB device then try that.
install windows first and then install linux, there should be a partitioner in the live cd. or just use wubi
You can make it the default option in the bootloader. Or you could reinstall the Windows bootloader, but it will not allow you to boot Linux without modification.
So that you can choose to load either linux or (usually) windows.
Buy and boot from a Windows XP cd.