Re: /boot separate partition
Although having /boot on a separate partition is not strictly necessary, sometimes it might be useful - for example:
- When you have an advanced filesystem you want to have in /, but GRUB cannot read it (e.g., the case with ext4 until some time ago); then you put the kernel, i.e. /boot, on a separate partition with an older FS which GRUB can read (e.g., ext3 -- or simply do not use GRUB, but that's another story)
- When you want your kernel and/or boot configuration to be available to other OS on a multi-boot platform; the other OS might not be able to access the / filesytsrem (e.g., ext3 or ext4) but might be able to read the simpler ext2; then you put /boot on a separate partition with ext2.
- A filesystem crash might prevent the machine form booting, if the kernel (/boot) resides on the / partition. If the kernel is on a separate partition, a sudden crash (power-off, for example) is unlikely to damage it since there very limited I/O on the /boot partition and it is sync'ed most of the time.