I'm kinda thinking that the first batch gelled and the second didn't, too. When the soap heats up in the mold and goes through a gelatinous stage, that's known as gel phase. Gelled soaps are usually a bit darker in color and ungelled soaps are usually lighter. Soap doesn't have to go through gel phase in order to become usable soap - some soapers purposely avoid gel phase. Ungelled soaps may zap a few days longer than gelled soap since the saponification process is slowed.
As far as the batch with the darker middle goes, I'll bet you got a partial gel. That's when the soap begins to gel in the center, but gel phase doesn't quite make it to the edges of the soap. You end up with a dark ring in the middle and lighter edges. Partially gelled soap is perfectly fine to use, too. It's just an aesthetic issue. It's kinda strange, though, that the uninsulated batch partially gelled and the insulated batch in the wooden mold didn't if the conditions were the same. Maybe your soaping temps had something to do with it?
I'm not sure about the cracking. Cutting ungelled soap too soon can sometimes cause crumbling. I don't know what to say about the different smells, either.
The soaps should be fine as long as they pass the zap test. To do a zap test, either touch the tip of your tongue to the surface of your soap, or wet your finger and rub it on the soap to work up a paste; then touch your finger to your tongue. If it zaps you (zap stings and tingles, like licking a battery head), there is active lye in the soap and it isn't safe to use as is. If it just tastes like soap, you're good. You will definitely know it if you get zapped. (And remember that ungelled soap can zap for 3 days or so longer than gelled soaps. Gelled soaps usually don't zap after 24 hours.)
Maybe more info about your recipe, temps, and method will help us further troubleshoot.
