Yes, they will grow in a 3 gallon, although personally I think that size is a little small in terms of moisture retention -- you will probably have to water them twice a day in really hot weather.

I'd say about 2 to 3 plants in a 3 gallon.

How many plants are needed to get a few good sized bowls per week? I'm thinking about finding a small spot for mine, too as I've about run out of space.

My understaning is that all the pods mature at the same time and then you just pull the hole plant out so if you plant them at the same time you need to blanch them then freeze right away or the other option is to sow every couple weeks just check the variety as most of them need long time to produce.