Can you rip and run commercial games from HDD? Probably not, but I bet any home brew games would feel pretty snappy compared to if you burnt 'em to disc.
If you've got a compatible sound card in your PC-98, GMAKER PLUS comes with a program that lets you create and use a CD Image on your HDD, but I've not used it.
The programs that run the board are all DOS based, and that limits you to 2GB FAT16 partitions, so you're not going to store lots of CD images on your HDD.
This video is really interesting. So are the programs he's loading at the end (which he said were DOS based) using that 3D acceleration that is only found on the card version of the FX?
You've got to reboot into DOS to run the board, but it includes a couple of graphics utilities that run in Win95 (16-bit Windows).
You can see him trying to run a couple of example programs that load data into the PC-FXGA's RAM and run from there.
Here's the fighting game funning properly ...
The other stuff, where you see him running "mixplay" or any "*.mix" file, is just playing back pre-rendered video from the HDD.
How about:
B) Providing more cool information about that piece of hardware.
What do you want to know?
Search YouTube for "PC-FXGA" and you'll find a bunch of videos.
Just remember, there was never any real commercial development for the board, so everything is pretty half-assed.