Beets will usually, in most climates, go to seed next year when it starts to get noticeably warm.

Your other questions are better discussed at Vegetable Gardening - GardenWeb. I think you will find there that you can overwinter beets with enough mulch and that some varieties may sometimes get a bit sweeter during the early winter.

yeah, mine overwinter....but they are pretty huge and gnarly, fit only for roasting and borscht......nothing like those little golfball summer beets. In truth, I mainly grow them for the leaves cos I am not keen on quite a lot of root crops (parsnip....gah!)...but essentially, they are biennial so will bolt to seed next year around May (for me).