With the food timer, you can just use the sort button on your inventory, storage boxes, feed basket or chiller box and it will reset all the timers.

I always thought the initial explosion was so hot it vapourised everything in a certain radius. Would an atomic frag work?

I’m pretty sure the intro quest to base building is optional. Once you save Gravy and friends you can just leave and go about your day ignoring Sturges. The teleporter later on is mandatory though but that only takes a few minutes.