As for the BIOS version for your motherboard, my experience has been that it's a non-issue. I just run whatever the latest BIOS is posted on the Gigabyte Web site AND for which there is a DSDT file in the DSDT database. But if you're going with the new 7-series motherboards with the UEFI (and not a "traditional" BIOS), then there probably is no DSDT. Then again, those mobos really don't need a DSDT any more anyway, right?
NOW as far as what OS goes with which version of Pro Tools, THAT, my friend is a COMPLETELY different story...and one that is WAY more significant to take into account. BTW, on a similar subject, I just posted this last night:
Pro Tools & Apple Qualified Hardware
According to this Avid KB article, ProTools 10 is supported under Snow Leopard 10.6.7 (note that it's not 10.6.8 which is the newest SL), and Lion 10.7.4 (not 10.7.5 which is the newest Lion). As for PT 9, do a search of the Avid KB for the corresponding article. THAT may answer your question as to why you are having so many problems getting PT9 to install.
Older versions of OSX
When you purchase Lion from the App Store, you'll get 10.7.4 (that's a good thing). Now that Apple has gone to this App Store delivery mechanism, it's a LOT harder to find the older builds of the OS. You might want to start doing what I do: Make a ZIP archive of whatever the current version of your OSX installer is (ex. I bought ML when it was 10.8.0), then make a backup copy of the ZIP (burn a DVD, buy a USB flash drive...whatever). Then when you see announcements about a new version of OSX released (for example 10.8.2), go to the App Store. You'll notice that in the "Updates" page, it will say that your ML installer (the original 10.8.0) needs an update.
Let the App Store update your installer to 10.8.2, then like before, make a ZIP of the new 10.8.2 installer & archive it somewhere. The next time Apple makes an update to ML (I think we're waiting on 10.8.3), just repeat the process: use the App Store to update your installer, then ZIP the new file & archive.
You end up with all the incremental versions as well as the most current version. If you need to re-build your UniBeast installer with one of the older versions of Lion or ML, you've got those incremental versions - just unzip one of the older versions & replace the current Lion or ML installer in the Applications folder. Then run UniBeast to re-build your install key.