-On a newer Cessnas with Fuel injection versus older with Carb, why is it that you start the engine with mixture "out" on fuel injected versus mixture"in(rich) on carb equipped Cessna? Also, why is there primer on older cessnas but not recent ones?

-I notice some airport that has both ATIS and AWOS. What is the purpose of having both?

-Aircraft with mode C transponder calls tower/ground with letter "A" after aircraft type when making initial contact. I recall there being more several more letters designating different equipment on ACFT. Where can I find this index/info?

thanks!!!