In regards to the question about using a cooler - certainly you can! It just needs to be big enough to house your pot plus the additional layers of insulation. In fact, many people use coolers as their hot boxes.

So far I've had success with cooking rice and lentils/beans, potatoes (for mashing), as well as braised red cabbage. I'm still experimenting, but basically anything that could go into a slow cooker would work, and especially things that wouldn't suffer if they are overcooked. I haven't tried it with any meat, and as I said in the article I'd be nervous to do so. But the starchy staples work wonderfully. I cook them on the stove for a quarter to half the time required, and throw it in the hot box to complete the process. 

Suggested recipe ideas are welcome - I'll give them a shot and report back!