joseph, your plates remind me of the Arabia plates i saw at Scan many, many years ago. the stacking was done with precision engineering of rim and foot to allow easy pick-up of stacked plates. maybe you can see them somewhere online, maybe ebay.
saki, a slump mold will allow you more options than a hump mold. most things on a hump have to be removed before the shrinkage forces the plate to crack from stress. so you have to be alert to the condition of the drying plate. a slump mold can sit around for a long time without causing a problem because the shrinkage is within the confines of the mold.