LH threads
No, it will not fit.
No, the outer diameters of the barrels are different, you would either need one of Sig's Caliber X-Change kits, or you can get a conversion barrel from Bar-Sto.
Yes, the SIG SAUER P226 9 mm Threaded Barrel is compatible with the P226 Legion SAO.
Yes, this SIG SAUER P226 9 mm Threaded Barrel will be compatible with the MK25 P226.
The SIG SAUER P226 9 mm Threaded Barrel will work with the P226 Legion. The SIG SAUER P226 9 mm Threaded Barrel should work fine with the SilencerCo Osprey 2.0 9mm.
The SIG SAUER P226 9 mm Threaded Barrel should work with your older P226. However, since there are some slight changes in the newer models I recommend contacting Sig to confirm. The SIG SAUER P226 9 mm Threaded Barrel is threaded for 1/2x28 so it will work with a 9mm suppressor sharing the same threads.
The Backup Tactical Sig Sauer P320 Full-Size 9 mm Threaded Barrel will work with that model P226. However, you will need to check with your local and state laws in regards to your ability to own this barrel.
Yes, the Sig Sauer P226 9mm Threaded Barrel will fit a P226 Tac Ops model.