This is in the Baerenreiter:
I got Baerenreiter as well so I believe we are synced then!
This is everywhere, but for example, in m 1, 3rd beat - do you repeat the E before playing the F?
Yes! You are still approaching the F from below, so the appogiatura is also below. In this case it ends up being the same pitch as the preceding note. If you listen to the video with Sergey Tanin he does this. In fact, as far as I can tell on a somewhat cursory listen he does all the ornaments properly and IMO with good taste.
MM 8 & 9, 2nd half of 1st beat, do you double the mordant at the octave?
Theoretically I believe you can do that. The lovely thing about baroque ornaments is that a lot of the finer details of execution are left to the taste of the performer. Another alternative is to do the right hand ornament short and quick, and the left hand longer and with more repetitions, since it's on a longer note. I'd suggest checking some harpsichordists' recordings and hearing what they do for inspiration!
M9, 2nd half of 2nd beat, how do you play the pince on top of the trill or mordant in the left hand?
Second beat right hand is E E (F) G, so you do an appogiatura before the F followed by a mordent, so something like E E EFEF G
Left hand is a trill so you start on the upper note, DC#DC#
If you play four quick notes like this you could sync these two ornaments between the hands if you like, but other approaches are also possible.