1.) Celeron 800, yes
2.) PIII up to the special 1000E (with 100MHz FSB). Because this was a low production processor, they didn't bother to list it in their compatabilities.
3.) Celeron 1100, yes, it's still Coppermine. But the PIII 850 will still beet it in some apps.
4.) Consider the iP3t from Powerleap, with a Celeron 1200 Tualatin. This combo is available with cooler for $169.
What's the frequency, Kenneth?