it also seems to be missing around 8.5GB of space for no apparent reason
Haven't you ever noticed that drive sizes on the motherboard BIOS and OS NEVER match! Drives sizes from the manufacture are base 10, while drive sizes in the OS are base 8, or something like that.
Anyway, manufactures list that 1000 MB = 1 GB, when actually 1024 MB = 1GB. Same for GB to TB, etc.
My 2TB HDD in listed in Windows as 1.93TB. My 60GB SSD in listed as 55.7GB.
It's no big deal. They all do it.
I believe Intel is the only driver (iaSTor) that supports trim when the Bios is set to Raid and the SSD is NOT a member drive of the raid Configuration.
This is true! And probably the reason that your SSD failed faster than usual! You need an Intel based chipset for TRIM to work. Else, get some kind of "garbage collector" for your SSD.
And TRIM is also only Windows 7.