Oshkosh fatal accident report--a question

A day or two ago the first official report on the Oshkosh Mustang
accident was issued, and not surprisingly at this point, it said
little. However, the local paper again cited a witness/pilot who put
the blame on the pilot who survived. He said that the plane in front
should not have touched down first. That makes sense to me--whoever
touches down first is going to lose speed much faster than any plane
still in the air. But then I wondered two things: 1) how would the
guy in front KNOW when the guy behind him has touched down? 2) since
the nature of the accident suggests that the pilot who died was
directly behind the other plane, why wasn't he laterally separated as
well? When two planes land in formation, it seems to me they are
always separated in two dimensions, not just one. Is there any rule
or custom concerning which side of the runway the lead plane would
take in landing?

I'm certainly not interested in apportioning guilt or in any way
dishonoring the dead, but I'd like to learn, and I'm particularly
concerned that Casey Odegaard (lead plane) is getting the blame in the
paper when the blame may not be all his.