Potatoes. They require the least maintenance and if you employ a small greenhouse (really, just a meter high, sticks and plastic sheets as cover) they can be grown all year round, yielding as much as 4 or even 5 harvests, depending on the potato type.

It depends on the region. I don’t know much yet, but I’d like a lot of perennials that way it’s less to plant every season. But it might be the case that perennials take a lot of work, idk.

Depends where you are. I like things I can grow vertical to maximize harvest per sq ft - okra and beans have been my most forgiving and pest free.