I am admittedly a bit torn between "buy once cry once" and "some aeration, even if not mathematically perfect, is going to be better than no aeration whatsoever."
To little aeration is NOT better than nothing. It can worsen the water quality if not sized to a bare minimum and don't forget that you will likely end up only running at night and not have all 24 hours of a day to turn your water.
Give me your surface area and average depth and I can suggest some minimum and more ideal requirements for the number of diffusers and pump output.
Would 15lb of FHM stocked two months before the panfish (if not also the bass and CC) be 'too many' FHM given their recruitment? My desire is to provide a large forage base to help support rapid initial fish growth.
This really depends on when the minnows go in. Late in the year and you might as well spend the money on pellet feed, you'll get more for your money. Late in the year does not let them reproduce much if at all. Seriously, the FHM's need to go in the pond in late April/early May and left to do there thing until the following spring, then add the game fish. Lots of pallets (15 to 20 for your size pond) under 1 to 3 foot of water makes them very happy and prolific! Here's my thoughts on "why" do it this way. If the FHM's go in in the spring and only have 2 months, you'll get alot of fry, but not so many full grown adults (the fry will be eaten quickly by the smaller gamefish). If given all summer, the fry grow to be adults and the following year your gamefish are to small to eat the adults, but will grow big on the massive amounts of YOY FHM fry. Now the adults are left to make more fry and are left to feed the game fish as they grow to be able to eat the large sizes. You get two seasons of forage compared to one.
