Heat cracks around holes are normal, which is one of the reasons racers prefer slotted rotors (though they eat pads faster). I'm still on my original set of rear rotors after 26K miles overall including 18 track days. I got a StopTech BBK on the front a while ago though so I can't help you there.
Just keep an eye out for deep cracks (especially those not emanating from a hole) and buy a micrometer so you can check rotor thickness periodically if you'll be tracking often, which I assume you will be if you're installing brake ducting. Another brake cooling option would be aftermarket rotors with better cooling (directional vanes, two-piece design, etc); I believe there are options that install on the OEM brake setup.
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