Good questions.
Nope, 100% of the information in this case comes directly from JR. Either from his posts on Facebook or from a few media interviews with him. JR is pretty much a loner. He always goes by himself. Then he comes back and posts a two line update on Facebook, and then says nothing more about the trip.
Most of his trips are very poorly documented. So there is no way of knowing the durations. There is no way to tell what he does or where he goes in Mexico, but he has posted a few pictures of himself eating dinner with random people in Mexico.
As for his trip to meet Jenny. Per JR, he went to Mexico on April 15th to spend five days with Jenny. She didn't show up, so he returned to the US on about April 20th. He then immediately began a fundraising effort to find her.