Forum search is not as easy to use as Google :)
Admin is affected by range to HQ, so only morale at the OKH/AGs level gives real bonuses all over the map, and the other skills while still important (every little 0.1% more to pass a test counts in the long run), work only for the area nearer the HQ unit (that's why I keep mine closer to the front in the important spots).
Priority of changes for me:
1) change OKH leader, as it's quite cheap and helps all units immediately, to Kluge (game should select and promote Model to 4th Army)
2) fix corps level commands
- fix overloads ASAP
- replace leaders below 5.0 average skill (6.0 for Panzer Corps)
- decouple infantry units from Panzer Corps
- assign all OKH/AG/Army level reserve divisions and brigades to corps
3) support units
- reassign SUs from corps that have many of them (some start with 20+ SUs and some with 0), I like a balanced approach so I try to have similar loadout of every command, with Panzer Corps getting more than Infantry Corps (mainly second Pioneer, two Nebelwerfers and different AA, while better-led infantry gets Stugs and Panzerjagers).
- move most of construction units, especially those with O.T. or Road in name to O.K.H. and Army Groups, so they could repair rail
4) look at armies and army groups overload and leaders
It is possible not to overload any army/corps commands, with a setup of 3/4 corps per army (12 infantry divs each) and one corps of 3-4 infantry attached to Panzer Groups 2, 3 and 4.