If you are only going to AutoX get the a203. They heat up really quick. If you take them on a track though you will kill them really fast. The r203 take longer to heat up but last longer on a track. The a204 are just the newer tire but from what I hear they are about the same.
The following is my opinion:
Hoosiers ware extremely quick even just autoXing can kill them quick. If you are just starting out I would recommend the Kumho Victoracers they last a lot longer and are more forgiving. The Hoosiers are better but unless you are squeezing that last tenth of a second out they are not that much better than the longer lasting and cheaper Kumho.
Heatcycling is a matter of taste really. Everyone has a different way of doing it and some say theirs is best even better than the Tireracks. I run a new set really hard at a 1-1.5 minute autoX then take them off for two days. If you just don't want to deal with it get them cycled already.