Well, this has been discussed before... But here's my take anyway:
Mixture: leave that out. We don't have EGT, and we can't feel the engine roughening as we lean it to peak. It's this limitation that makes me say leave it out. Besides, it's really not that hard to do, change altitude, lean the mixture to about 50 rich of peak...
Prop: well, it is sort of modeled. Just finish the prop model HTC
Blower: this could be cool. It really wouldn't effect ACM much, but the heavy aircraft would feel more realistic with blower controls modelled.
Oil Cooler/Cowl Flaps: model them! It'd be a nice touch, even though it wouldn't really effect the game much, it would add to that immersion factor...
Of course I think there should be an "automatic" function to handle all this, just like we've got the fuel now...
blk