I've had experience using all but one of the programs you named (mainly because Samuel sent them to me in hopes that I could find FF9's saw wave sample, but alas, it hasn't worked). I don't know how Ff9s.exe works, but I'll help you with the others.
Thv.exe, Thv072.exe, and Thv.07273.exe, are primarily designed for instrument sample extraction from FF8 PSX, particuarly from the FF8.img file.
If you are comfortable with DOS, then it should be easy. The idea is the same with all three, but I'll use thv.exe as an example.
At the command prompt, go to the directory where thv.exe is. Put one of the four FF8 PSX cd's in the drive. Now, here's where it'll get slightly tricky. I know some basic syntax for it, but I don't know any command switches.
I don't have much time, but here's an example of it. FYI, my cdrom drive's letter is "j"
thv.exe j:FF8.imgIt'll start extracting a bunch of stuff as wave files in the directory where Thv.exe is.
Hit the pause key every so often so you can view/delete the extracted stuff from windows explorer. I think you hit either the pause key again or the space bar to continue. It'll keep going until it goes thru the entire image file.
Hope that helps!