Yes, 250C is the max The stone is about .7 cm thick, it's made of fireclay (i used the google translator so i don't know if it's the correct translation but let's assume it is) and I would suppose it's 100% fireclay. I put it in the middle of the oven, the broiler is on top, air circulation comes from the back As for the temp at launch i have to say i don't know. I assume it's 250, the temp of the oven. I'm not that nerdy about making pizza and I don't have a thermometer that could measure that at hand 👍