Linux bootup q?

Hi,
Could anyone answer few questions on bootup sequence of linux that i have.

1.What is the typical size of a bootloader? Since the booloader code starts
from 0x7c00 and can touch till 0x9A000, Can i assume that the max size of
the bootloader could be 0x9a000-0x7c00=0x92400[ 585kb ]. What if the
bootloader exceeds this size?

2.Will the bootloader use the magic number of the(0xAA55) of the kernel
header? If so, when?

3. Is the BIOS setting the IVT for loading linux standardised? (I asked the
because some vector numbers are used by the bootloader BIOS calls). If so,
where can i get the details?

Thanks
Uday