I would have put up a basic trellis last year, to get the plants off the ground. They can be susceptible to fungus if they don't get enough air movement to help keep them dry. Plus, it lowers the number of bugs that will come in contact with them. But anyway, I usually put my trellis up right after the plants show about a foot of growth. I was late last year and regretted it. Having the trellis up early simply means that you can start training the plants as soon as they are ready, instead of having to untangle them and training them while trying to not break them in half.
It's entirely possible that one or more of those that didn't grow last year will come up this year, but don't expect it. They are generally hardy plants and even if they are late, they usually show pretty quickly and get some growth.
For second year plants, I'd count on 15-20 foot plants and some usable flowers, especially with that many plants. I planted 3 cascades 3 years ago, and the second year got enough to brew with and some left over. Last year, more than I could use and will probably give some away again this coming year.
