SAT2 has 3 operational airbridges to use. Gate 37, Gate 30/88 and Gate 32/87. During the first and second lockdowns when Stansted only had SAT2 operational the airbridges at Gate 30/88 and Gate 32/87 where used regular by most airlines operating at that time. Turkish Airlines, Pegasus and Air Moldova to name a few. Titan would often use these gates for its flights to Loudres due to the amount of wheelchairs on board making it easier to gain access via the ramp to gates 81-88.
In terms of what has been mentioned of SAT3 in my opinion the gate 40-50 area is good. It’s functional and works. It has had some work to it in recent times with new toilets and touch up work. Also MAG where in the process of remodelling all gates in this area. If you fly through these new styled gates are 43,48 and 50. But due to money constraints this has been put on hold.
The TTS dose in fact run to SAT3 though a station was never fitted out to the satellite. It’s is just a huge unfitted out area sitting below the satellite. The tunnels and track do actually run past SAT3 to where a fourth satellite would be built.
SAT3 was built with a purpose and that was to me cheap and easy to use for the airline that requested for it Ryanair. BAA original plan for Stansted was for it to have 4 satellite buildings all built the same and linked to the terminal by the TTS expect SAT2 to allow for domestic flights like it does.