I could be wrong ...
Mode S is not ADSB-Out but you can add ADSB-Out to quite a lot of ModeS transponders by installing/adding a combined GPS Rx and antenna
ADSB-Out is not Mode S (or A or C)
ModeS responds to radar intercepts (where radar exists)
ADSB-Out dumps identity data including height and GPS Position continuously
ModeS only dumps id data including static pressure if (and only if) it is radar interrogated.
ADSB-In cannot receive Mode A, C or S signals, it only responds to ADSB-Out signals.
At the moment you don't need a Mode transponder in Class G or D but you do need a Mode transponder in Class A, B, C and E (and maybe above 10,000 ft)
ADSB-Out squawk codes may make sense to ATC but the SkyEcho can, and should, be fixed to 1200 but which doesn't seem to be tracked by OzRunways.
I'm still trying to work out if my occasional bird of choice has ADSB-Out (Trig TT21) without crawling through the plane looking for the GPS source. Either it doesn't or it has a squat switch but doesn't show up on ADSB In on OzRunways.
Cheers and may Santa bring you a SkyEcho so you don't need to wait around for (yet another) government promise to be fulfilled.