well, between him openly expressing doubts about the flood, spending lots of time on the net, and having no intention to return to MS-ing.. i'd say it's pretty clear that he's mentally exiting, it's just not clear exactly how far along yet.
Auxiliar pioneering in April seems like the piece that doesn't fit, but he could be doing it out of pressure from his wife and family, it is quite likely actually. if his goal at the moment is to keep face with the family and the congregation, and he had the circumstances to do it, doing the aux-pio would make sense since with the low 30hrs and increased participation, anyone who can but doesn't would look at least somewhat suspicious.
in the meantime, keep alot of communication with him. I, feeling very comparable to how you describe yourself, can definitely see the benefit of opening up to eachother and being united in your dissent. perhaps laying it all bare on the table is too risky at the moment, but you could drop clues similar to what he is doing - expressing doubt about just one particular teaching (try overlapping generation), in a casual way, and see how he responds. if he appears too shocked, you could always tone it down by saying "oh, i'm just confused by it a bit, i'm trying to understand it better".
by the way, i really like the way you put your points in order in the opening post.