Doug Lenat is very much still active in the project. He doesn't do as much work building the ontology, but he plays a role in how various projects develop and provides a lot of feedback.
I'm also a Cycorp employee, so I can say a little bit at least about (1) and (2).
1) We often use HOL. CycL isn't restricted to first order logic and we often reason by quantifying over predicates.
2) I don't know where you could read an explanation of it, other than the general problem that NLU is hard. It is something people at the company are interested in, though, and some of us think Cyc can play a big role in NLU.