Well that is a lot of electronics. If your well water is already working for the house I would advise you to retain that system and not connect the two systems at all. Connecting them will make the systems much more complicated and comes with the danger of contaminating your drinking water. The system can be much simpler if they are separate.

The fill for the tank can be much simpler. The well pump is likely already activated on pressure drop, so you can just hook a line to a fill valve (this sort of thing https://www.amazon.com/Trough-Matic%C2%AE-Stock-Water-Tank/dp/B000B4GTPK/).

Just connect the spigot to your house supply and get rid of the extra components. A vacuum breaker on the spigot (one of these https://www.amazon.com/EZ-FLO-20199-Anti-Siphon-Vacuum-Breaker/dp/B00LEMRVIW/) is all you need to protect your house water supply for that application. You can save a lot of money that way and get rid of the hazardous interconnect.

You don't need two check valves after each pump. The check valve prevents water from flowing backwards through the pump when it is not running, a completely different function from a backflow assembly like a double-check assembly or RPZ. Only one check valve is needed and it should be mounted immediately after the outlet of the pump.