Firstly install the latest version of udev from www.slackware.com
(do a package search in 'current' and use pkgtool)
In the 2.6 kernel you don't need to enable scsi=ide emulation for cd writers as in the 2.4 kernel. So you might encounter a problem if you are passing this parsmeter in via a boot loader (e.g lilo - /etc/lilo.conf)
Presuming it's an ide cdrom, it should be created as hdb or hdc etc...
OKay, and check your /etc/fstab file. You may find that /mnt/cdrom is trying to mount the wrong device from /dev
go into /dev and run 'ls -l hd*' What's the output?
Othere than that udev can be a bit funny at times. what's the output of 'dmesg |grep -i cdrom' (or similar).
Not sure about you X problem. Have you run the .sh file for Nvidia. I seem to remember that i had to get a moded version as it (the one from Nvidia) didn't work with Kernel 2.6.9. BUt that was a few months back and I presume they have shipped an update.
Bascailly the NVidia driver isn't too hot. IMHO. Have you moded the Xorg.conf file as outlined in the help files?
Anyway, you're not alone with these issues - I've experience a bit of both in the past.