Great article! I've kept these singly in 20 longs with no issues, but I agree, it's best to keep them in a 30g or larger as they will breed out into several generations with older offspring assisting the adults in caring for newer generations.
Similar thing happened to one of my Aqueon 55/75s, I it left unoperating for a couple of weeks, and when I set it back up, it wouldn't turn on - turns out, something was creating a blockage in the impeller area.
Quietflows don't have the best design, but they're pretty tough.
Jungle val and trident java fern are wonderful lowlight plants. They take a little while to acclimate and usually melt quite a bit at first, but once they get going they grow pretty fast from then on. Just be sure they are provided with sufficient, adequate lighting as well as the regular dose...