Have you tried cold-brewed coffee? It couldn't be easier: put grounds is water bottle before retiring and decant in the morning. If you pour slowly and don't mind a few grounds there's no need for a filter. If you do decide to heat it up it's easier to warm the prepared beverage to drinking temperature than it would be to take the water up to brewing temperature and then wait for the brew to cool.
As for hydrating times work at lunchtime is my laboratory time. I dehydrate lots of different stuff and practice re-hydrating it at work. Everything's different: mashed potatoes re-hydrate instantly with even cold water and are very satisfying. Sweet potatoes, squash, etc. are pretty good in a few hours if you drink the broth with it. A lot of stuff is fine as is, especially stuff that's dried to leather rather than crispy stage.