So Dr. Bickle had some positive responses to the questions I emailed him. He suggested that I read Paul Churchland to get some hints at answers on the "dimensionality of language" questions, and I just ordered the book. He was skeptical of my suggestion that the subtraction paradigm could be used to find new conceptual points, and he suggested that I try to work it out. This is consistent with what he said in the 2000 paper, so it doesn't come much of a surprise. I'm going to dive into Matlab to try to work it out.
Ali Minai also responded to my questions, saying he'd be happy to meet with me, and that my interests are in line with what he works on.
So there's an outside chance that I'll be able to stay in Cincinnati and work on a PhD. I don't have any qualms moving to another place, but I'm really coming to like Cincinnati and the community that is developing here.