driver installations are the same as any other bit of software. if it's from source, it's ./configure, make, make install, if it's an rpm .. rpm -Uvh file.rpm
where they go to doesn't matter, a kernel module will end up somewhere in /lib/modules/linux-2.6.8/kernel/drivers probably, but all you need to know is that it's there, and running "modprobe modulename" works.
the chances of there being no default driver for a video card are somewhat marginal though....
theme... not a clue, you've not said what window manager you are using.