There's no single file that contains the boot information. Nor is the method of booting uniform across all platforms and distributions. There are dozens of bootloaders, each of which have their own configuration files in various locations.
boot sector
grub ana LILO are the two boot loader in Linux
Diskless Remote Boot in Linux was created on 2004-04-01.
Boot control block is typically the first block of the boot partition (boot block). It contains information to boot the OS from the disk.
/boot
It contains information about the disk or logical drive.
If you have a USB drive and your BIOS supports booting from a USB device then try that.
In a dual boot system, the list of available operating systems is typically found in the boot loader configuration file. For systems using GRUB (the most common boot loader for Linux), this information is stored in /boot/grub/grub.cfg or /etc/default/grub. For Windows, the boot manager configuration is maintained in the BCD (Boot Configuration Data) store. Users can modify these files to change the boot order or add/remove operating systems.
No version of Linux is officially supported by Boot Camp. Assuming when you compile Linux From Scratch you include support for the Macintosh's hardware, it will work just fine when using Boot Camp to prepare the system.
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.
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.
As there are hundreds of Linux CDs, it is impossible to provide a comprehensive overview of what, if any, boot options they may provide.