appreciating you rquest for knowledge, i cant see beyond the fact that you have showed (and if we were all to have an estimate) that at the current match ratings we all obtain the deviance between home and away is approx 1/3 of a full rating point for certain stats (RB / ID being the most visible)
It would be interesting to know how the difference widens (if at all) as we all progress up the rankings...
i cannot see how further investigation at these levels is going to show up anything new....
i think these numbers wil become more interesting in a few seasons then multiply a TIE / CT into the equation and then we may have some more interesting data...
also at these levels the random factor has much more do to with the results...