CMSport

Possibly also 0 in G4X.  When adding trigger modes to the G4X, if the engineers have confident info of the normal trigger offset they will build it into the trigger code so the offset is close to zero to make first time setup easier for new users.  I cant tell you off the top of my head whether the G4X 2NZ mode has the offset built-in or not.   

No, that doesnt prove anything. The valve is a solenoid, a stepper would have 4 or 6 pins.  Do the test suggested.

Yes, even the old G4+ can have Lambda input via CAN.
As for how many inputs, there is not really a limitation, although you may run out of channels that you can assign to the inputs.  But as a rough guide at present you can assign 8 CAN lambdas, 8 generic CAN analog inputs, 8 CAN digital inputs, 8 CAN EGT inputs, then there are a few random dedicated channels such as steering position and antitheft etc.

Yeah for temp sensors connected to analog inputs you need to use a custom cal table - usually cal 1, 2 or 3 is easiest.
If you use a 1Kohm pull-up resistor then you can set the cal table input units to be ohms and enter the resistances from your workshop manual directly into the table and it will do the conversion to voltage math in the background.
Most common Japanese sensors will be based on the bosch curve  (you can confirm by measuring resistance of your sensor at 20degC it should be ~2500ohm).  There are resistance and voltage tables for the most common sensors you can reference in the help file: Technical Terms and Reference > Sensor Calibrations