Yes, definitely. I don't have any corruption index, my thinking is this:

To really steal a lot you have to know the system from which the money comes from, and Afghan officials didn't know the US system. A corrupt Afghan officer could at most steal all the funds of his unit, a US contractor could siphon the US budget with all the tricks contractors learnt over the years.

* "If they required our logistics after we pulled out- at what point could they be weaned?"

That's a question that requires very detailed information to answer, and I'm not sure is the best one. IMHO, the better question is: "How much damage (by manpower and money) would the US sustain were it to try to supply them instead of what the US did?".

I don't think that keeping logistics and supplying parts to the airforce was a significant burden. At the worst case scenario, they'd have collapsed a bit later and there would have been more time for an orderly evacuation.

* Beyond self-absorption, The US never had a workable political strategy for Afghanistan. The DOD cannot come up with a political strategy (generals are just bad at this), and recent Presidential administrations are too remote and have little area expertise, they left things at DOD for too long. The US needed a structure with much more civilian input.

The reason Iraq turned out very slightly better (and we should remember just how many people ISIS killed) is that Zarqawi and his successors insisted on blowing up random Shiites, while the US stumbled into a semi-workable political strategy ('give most power to the Shiite majority regardless of what Sunnis think'). So when the insurgency turned into an ethnic civil war, the insurgents were on the minority side. Perhaps this was merely an bloody accident, but even an accidental political strategy has effects.