2. Have you tried to fit an S2 mag release on the TSO frame? It tried on a TS and it came out way too short. Is there something I missed?
You didn't 'miss' anything. The S2 mag release will physically fit a TS/TSO frame, however good luck getting any TS/TSO mags to seat

If you compare a TS mag to a standard CZ75, you'll see the TS is wider. This means that the S2 mag release is narrower (inside of the "U") than a TS one, because of the mags.