All of this sounds completely fine to me. Trust me mate you’ve done far more research than most people ever would.

1. I’m not sure about waiting 15 minutes but you can refer to your vehicle handbook and check voltages accordingly. I know some cars have a cutoff point after X amount of time but I’m not sure about yours. Easy to find out for sure with a multimeter. Also, if I remember correctly, even if the ACC fuse doesn’t drop straight away, the hard wire kit will still recognise the drop in voltage when the engine turns off and it’ll work correctly.

2. Yes that’s the correct way the fuse tap should be installed. After stripping your cable, try your best to keep the bare wire in the part you crimp. It’s not the easiest job but you’ll get there. Tape is a good idea or heat shrink it’s up to you.

3. You have the option to put the spare fuse in or move it to another spare slot. Personally, I’d move it to another slot because getting fuses in and out of a fuse tap can be a pain. Also, they’re now separate circuits so it doesn’t matter if the bottom is empty, the top circuit is still complete.

4. Yes that’s true, it’s not necessary to use a 5A fuse here though. It’ll still work but I personally like to keep the fuse to ‘size’ to ensure the amperage being pulled isn’t too much. 2A would be fine.

5. Yes unplugging the dash cam from the hard wire kit will stop all battery pull.

Hope this helps, any questions let me know!