Why are you using the latest driver release with a tnt card, there has been nothing in release notes regarding a tnt card for awhile that I've seen.
Your second point may be correct with a tnt, but the driver does support multiples X screens and multiple X servers on the same card with geforce chipsets, on the 2 ultra, 4, and fx (these are the only cards I've tested).
"..the triumph of evil is for good men to do nothing."
VIDIA video driver RPMs for Fedora
:: see yum repo at livna.org