For the USB powering issues, I would first try this:
https://www.amazon.com/PortaPow-Micro-USB-Cable-Charging/dp/B0088HTYUE
It's a charge only USB cable.
Consequently, you can also apply tape over the data pins on the large USB connector to prevent data from passing through. Here are instructions for that:
Make a USB Cable 'power Only': 6 Steps
Yes, it's called a USB condom.
I've been drooling over one of these units for a long time. You can buy them on Amazon.de and avoid the VAT charge too. It's one of the last things i'm going to spend money on after the more critical items are fixed up. Soft top gets fixed ahead of this!