Did McCain know about it, and when did he know?

Yes, indeed, this sums it up:

"John McCain's campaign manager and Freddie Mac essentially had what amounts to a secret half a million dollar lay-a-way plan. For almost three years and as late as last month, Freddie Mac made secret, monthly payments of $15,000 to Rick Davis's firm, apparently in exchange for providing special access to a future McCain White House. If McCain knew about this, his presidential campaign should be in serious trouble. If he didn't know about it, he ought to fire Rick Davis immediately," said David Donnelly, Director of Campaign Money Watch.