Close to half of your issues would be greatly minimized if you top worked disease resistant scions or buds onto your existing trees. There are several scab-immune varieties out there that also have good resistance to cedar apple rust and powdery mildew. This site has great descriptions of a good chunk of the disease resistant varieties out there:
https://www.orangepippintrees.com/search.aspx?ps=35 Then you can go to the fedco, burnt ridge, or other websites to buy scion wood for your chosen variety. It will set you back 2-3 years of production but it would also disrupt the life cycle of a lot of pests and pathogens without fruit to support them.
Are you willing to spray kaolin clay spray onto the apples a few times after petal fall? It's organic and it's a huge help for codling moth. I would understand if your not spraying in part because of the hassle factor.
I know absolutely zero when it comes to Japanese beetles.
