I'm with THG on this one, ive never heard of a ballast running different watt bulbs, they normally say something on their tag. mine says 400w hps/mh for example......
I personally like my temps at 74-78 during lights on, if i saw 85 or above i would lower them, but hey, thats just me.
As for the light cycle, from what ive researched, autos are best grown under 20/4. if you have 24/0 you would just be wasting electricity for almost no gain. I'm using 20/4 on my grow.
Im using a 400w mh bulb for vegging, and for flower (which is soon, my 2 babies just showed they are beautiful ladies) i have a 400w hps. for flowering you definately want to bump up lights and get plenty of red spectrum in there.
Did you change your fan for your light? just wondering....