Infinite batteries should work. On how to use the coal generator: check the universal electricity wiki. About this unsealed stuff: in the newest recommended version, two special blocks to help you seal a room are included. There is one to let electricity in and out of your sealed room, called the sealable copper wire, and one to let oxygen in and out of your room, called the sealable oxygen pipe. replacing the oxygen pipe that goes through the wall/ceiling with the last named should fix that problem. Also, you have to turn on the sealer in the GUI. If it still doesn't work, it might be that the moon dirt isn't actually impermeable to air. I haven't tested that out, apologies for that. Anyhow, replace walls, floor and ceiling with tin blocks, those did work when I tested it.