Commercials appear between innings when players are warming up, not in the middle of a drive for a score. Billboards on stadium walls go back to the Babe Ruth area...just not as prominent as today. As far as the spending, there's really only three teams that use it to their advantage: Yankees, Mets and Bosox. I don't disagree that it's a problem, I think teams with limited payrolls but strong scouting can still win: see 2003 Marlins, 2005 Astros.
As far as the game being fixed, it's a controversy where there will be people on both sides. I really believe the networks control the outcome of the game. Pitts burgh is a small market, but big big market for tradition and merchandising. Seattle probably sells 1/4 of the Pittsburgh's total sales in merchandise. But, I don't expect everyone to buy the "conspiracy" theory...it's a bit outlandish except when you watch that game. I don't think the league would have fixed it for Buffalo to win over power markets like NY, Washington, and especially Dallas. I think they knew to just let us play and it would all work out for them.