I have added a pre-check and set-up guide here.
The only soldering required is to solder the battery extension cable to the charging board. If you are not comfortable doing this I can do it for you prior to shipping but there would be a small charge.
Unfortunately not. The Zega Mame Boy kit replaces the original Gameboy PCBs
No, this kit uses a lithium rechargeable battery than can be supplied with the kit (within the UK), or you can choose to purchase your own.
I purchase all my batteries from Aliexpress. You can order them here. See more info under Recommend Batteries
Technically yes, but you would need to install all the required drivers manually for the LCD, GPIO input and audio output yourself. I do not support 3rd party images. If there are any issues while using your own image, I'm afraid I cannot help. Why not do it the easy way and download my pre-configured image