Hi, I think this is great! Which school is it and when do you anticipate having the sale? I will come by and buy plants!
For the first question, I am not at all focused on organic seed (should I be? I don't think I ever thought about it...) I would definitely choose the second orange tomato, Moonglow, because it won the Heirloom taste-testing, and because it is ready sooner (80 vs. 90 days is a lot when you are waiting for garden tomatoes!) and because the other one says it is sweet, and that is not my preferred tomato taste.
The Silvery Fir Tree tomatoes say nothing about flavor, which makes me suspicious. The hanging basket potential could be good or bad; I think it would not make me enthusiastic, but it might interest people with a different yard / sun setup.
The Speckled Roman look like fun, and I do think that part of the pleasure of an heirloom tomato is how it looks, and that you know you are eating an heirloom tomato even before you taste it. I would buy this if you were selling it.
I was going to say that I would go for the orange cherry tomatoes because they were bigger, and then I reread the description and saw that they are smaller. I'm annoyed with small tomatoes at the moment because I have had a couple of bad exeriences with them going soft very fast. It is, of course, different when you can pick them right off the vine and eat them. But 1/4 inch (the orange ones, if that is not a misprint) seems very small. Your last pick, the Velvet Red, are an inch, and won a taste competition; that's the one I would want.
Last year was the first year we had enough sun to grow tomatoes in our current location(we took down a tree), and we grew five tomato plants, each a different variety, mostly heirloom. So that argues in favor of offering a variety. While you are at it, why don't you grow some basil plants to sell, too? Even people who only have windowsill space can grow a couple of kinds of basil, or a couple of plants.