Michele, I'm sure your Crossvine will be fine, as it is a native plant that no doubt is wired to recover from these types of Spring freezes. Your Calycanthus should be fine, too. I have one in full Sun that has done pretty well, although I've noted that mine in part shade grow faster and seem a little happier. That is one of the best shrubs ever for fragrance! :)

I'm also wondering about several of our plants that suffered in that freeze. Our newly planted sycamore tree has been brown ever since, as has our tulip poplar. The azaleas also look really really bad. Could that freeze really have killed these?

The buds/blooms on the azaleas are probably gone. I'm getting some blooms on the bottom and inside the plant, I suppose those buds were insulated by the rest of the plant.

Azaleas usually shed and get new leaves after blooming, so that is likely what happened. My leaves look dark and dry and will probably fall off, but that happens anyway. Azaleas are evergreen,so this can't kill them,but if they had any tender new growth, that may be dead, but they would get more.

Keep watering, and if they do bloom, right after blooming trim off any dead looking foliage and fertilize.

I have three tulip poplars, and they didn't miss a beat even with the crazy weather. No damage whatsoever or setback. I have lots of azaleas, many different varieties, no problem there either.

I must say that was the most unusual late spring freeze that I have ever experienced. After four nights of below freezing temps (2 in the mid 20's), I expected to to see hundreds of Hostas collapse in a pile of mush, so far haven't found a single one even slightly damaged! A pair of Boston ferns (forgot to bring them inside) sitting on 3 & 4' pedestals between 2 Hydrangeas were untouched, while the Hydrangeas suffered major foliage, and I'm sure flower bud, damage.
The only plants that were damaged were Hydrangeas, and only about ½ of the total and very random. Two trees (only)sustained a direct hit and they were adjacent deciduous Magnolias. Both had just finished flowering and produced new foliage. Six other similar trees suffered no damage.
Even the remaining Camellia blooms were apparently untouched and no Azalea flowers were affected.
Call me Lucky!
Rb