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I have a quick question. If one is using a bootloader such as Grub or Lilo, what does the kernel need to start from?

Thanks

you can make grub to load a number of sectors with
the chainloader +x command where x is the number of sectors to ,load. So you can load just the bootsector. It is loaded like by bios that means there are no differences between grub and bios booting. You can also load more sectors eg.
chainloader +50 to load the 50 first sectors from a disk.
You can create an image and dont need to care to get the other sectors loaded.
In both ways the pc is still in realmode, starting adress of 1st sector is 0x7C00

i wouldnt worry about chainloading sectors. use a basic FS like dos FAT12 (standard for floppies), and use a kernel that is a recognised file format (eg: ELF, AOUT). and grub will load it automatically.