"HC Fownes, Emil Frosch, Peter Robertson, John McGlynn, Emil Loefler, and WC Fownes ~ it seems they've done a good job identifying the cast of characters, now if they could figure who did what and when we'd really be on to something."
Having just spent the day with the club's historian in his rather historic document and material fillied office and with others out there and after going over these very things it seems the idea for Oakmont, the purchase of the land, the formation of the club, the stock subscription, the conception for the course and the execution of the golf course in 1903-04 was pretty much the idea and work of Henry Clay Fownes.
Perhaps this time we don't need anyone on here claiming Fownes was too much the novice to do what he's been given credit for with Oakmont and that consequently someone more knowledgeable had to have been brought in for which that person was never given adequate credit. Perhaps you should look into, in detail, who H.C. Fownes was and what he was capable of, or at least ask first, this time.
There were a couple of others between the initial construction with groundskeeper Frosch and McGlynn such as a man named McPherson and another by the name of Van Hagen.