Thanks. I emailed them about their compost and they were really helpful. So if I don't get any other input from anyone, I'll go with them for the mints.
The 5' tall wire shelves arrived yesterday, and the Daughter put them together for me. (She's been home with an evil cold, bored to death, so it was the high point of her day!) Light is up top, and I think I'm going to have to adjust the shelves a bit as the hot pepper plant we bought some time ago at Waitrose is already too tall for the bottom shelf as we have them set now. The other plants are doing well, although now that their distance from the light has changed I'll have to wait to see if they stay happy.
The whole thing doesn't look toooo bad in the kitchen - I have a large piece of white muslin wrapped around it, top to bottom, to "keep the light" and warmth in - need to get one of those mylar reflecting blankets, I think, as it will be more reflective, although the white sheet is better than nothing. Have also put sheets of aluminum foil on the floor underneath, so the light reflects back up to the plants.
Will have to see how it goes with the tomatoes. I was going to put a bucket next to the shelves and put the tomato plants in there, and then train them up the side of the unit. In the summer it will get a tremendous amount of indirect sunlight, but if memory serves tomatoes really want a lot of direct sun. So we'll have to see if the light can handle that. I'm hoping!