I don't know that you're going to get any specific answers, since most if not all of the programs consider the information you're looking for to be proprietary information.

However, for what it's worth some others who claim to know have said that as to questions 1 and 3, there is a cross-payment in principle, but some airlines have an agreement between/among themselves to offset flights bought for miles from one FF program on another carrier with flights bought using miles from that carrier's FF program on the initial carrier.

As to your question 3, I think many of us would like to know the answer to that question.