Re size of pots, the plants you get from T&M aren't huge so a 12"-18" container per plant would be ok for the first year, but I'd pot them on into bigger pots each year and include water retaining gel and feed them with organic liquid seaweed such as Maxicrop to be on the safe side. Might be easier to just pop them in the ground.

I've read that you should get some berries next year and a really good crop from the third year onwards, but this is only my second year of growing them, so I'm really interested to see what happens!