ah.... I have 2 of these puppies, very nice!
MAX HD size is 430MB. sad but true. Software bios add-ons like DiskManager or EZ-Disk that bypass this limit, do not always work on GG cards UNFORTUNATELLY. there is a 50-50% boot success rate. I have tried it many times with various debug options... what you can easily do, is create an amiga partition of ~430MB and assign it as a PC-HD on the GG BIOS...
if you want a soundcard for your GG, try to get a SoundBlaster 8bit one. they always work 1000%. newer models work too, but they tend to choke (due to isa bandwitdth of the GG I think)
A Cirrus Logic 542x vga is nice too
btw, the english GG manual is huge, I have not seen it online anywhere...
ask here what exactly you want and I will try my best to answer you...