hi i was talking to someone about dahlia tubers today, who said that they have potted their tubers already, and hope to take and grow cuttings. I think they do it to sell the cuttings rather than plant. I've had a quick look on another dahlia website, and it seems simple to grow and take cuttings. It doesn't say what you do with the tubers once you've taken the cuttings from them.

I'm new to gardening and dahlias, and just dug up and split the tubers out so that they survived as much as anything else. the plants had obviously been left in over winter for a couple of years, and the tubers were a tangled mess. Am i right in thinking that only the fat tubers will be any good?
or should i pot some of the weaker looking ones and try and grow cuttings from them?
i don't know what happens when you pot them, do you get only one shoot from each tuber?
and then if that is removed, is the tuber useless? or could it still grow another in time for the season?

i know some of the dahlias were show flowers, but some had grown from dropped seeds and were no longer true to type. I have no intention of showing them, but it seems daft not to keep them as they were intended.
also the ground i dug them from is still bare, should i grow something in here as cover or to aid the soil until i'm ready to plant out. i would appreciate any help thanks.