It is possible to store your oxygen tank lying down if there is no possibility that it can roll around and bash into walls or other obstacles that could cause a spark, rupture the tank, or knock the valve off the top of the cylinder. The better storage option is to store them upright in a rack where they are secured to prevent them from falling over.
Fermented tofu will not keep indefinitely but has a significant shelf-life of between six months to a year. The fermentation process continues, even if refrigerated, and it will reach a point beyond which it will be inedible. This expiration date is often determined by the type of ferment, as some ferments can take six months just to reach maturity.
All canned foods have been pre-cooked, so it is not necessary to heat canned food from a safety point of view. Heating up the food will enhance the flavor of the canned food and make it feel like a heartier meal, but this is not necessary. Canned foods can be eaten cold, right out of the can.
You cannot start a bee colony with a queen bee alone. A bee colony is a community of bees, where different bees have different functions, and they all depend on one another to fulfill their part for the colony to survive. The queen is pretty much helpless on her own and will not survive on her own, nor be able to build a colony without other bees.