Not all del sol's have a/c. I think it was optional in the S and Si models, and standard in the VTEC model. I'm not absolutely positive on that though... As far as things to look out for, like you said leaky roofs (93's are the worst by the way, there was a factory recall) Also, wrinkles in the door panels right below the door handle. Faded paint on the rearview mirrors and roll bar... I don't really know what else, all of those are pretty minor things, as far as I know there are no big mechanical problems commom in del sol's. Hope you find what you are looking for.
~Morgan