1. grub-install /dev/hda should work (assuming your boot disk is hda,
of course). If you're unable to boot to the partition that has
grub-install, Knoppix will get you a fabulous repair system that
has it. It's also a good idea to save off your MBR once you have
a working system: dd if=/dev/hda of=mbr.bin bs=512 count=1
Alternatively, I believe you can actually use Windows NT/XP's boot
loader to boot Linux. You'll need to copy out a workable MBR for
the Linux partition, save it off to the XP partition, and then
call it from XP's boot.ini. See the Gentoo documentation for
2. Sorry, don't know how to do colors. AFAIK the color directive
applies to the entire grub screen, not to individual entries, but
grub is so configurable that I'm very likely wrong.
3. Redhat's grub is not customized, so Mandrake's should be the same.
(If not you can just grab a grub RPM from somewhere.) You should
be able to copy Redhat's (or some other) splash.xpm.gz into your
/boot/grub directory and add the line
to your grub.conf to get it to do what you want.
And of course in all the above you need to adjust hda, (hd0,0), etc.
to your own requirements; the grub manual should have adequate detail
Hope this helps.