Question AIO fan flow

[rcflyercomp]

I am building a new computer using a Strix Z790-e wifi II board. Actually, this is two questions, but the primary one is regarding the AIO cooler installation. The way I have my setup going so far is that I have 5 intake fans, and 4 exhaust fans. However, three of the exhaust fans are on the AIO radiator, and I saw a video that makes me question this arrangement. The AIO is mounted at the top of the case with the fans below pushing air up through the radiator. Should the fans be inverted to make them intake fans and pull outside air down through the radiator? This is the first time I've worked with radiators, so any info will be appreciated.

The second question is what is the reasoning behind putting a pair of DIMM modules in the A2 and B2 slot before putting them in the A1 and B1 slots. Logic to me says the no 1 slots should be populated before the no 2s.

Thanks again.