Yes, you can charge the animal camera with an external power supply. For the DC connection you need a 6V/1.5A adapter with 3.5mm (outside) and 1.3mm (inside) plug. 

Pretty sure it's water proof, Mine has been outside since I bought it. It works fine. 

This depends on the amount of solar energy available (sunny day or cloudy), and whether the power bank support charging itself and connected devices (not all power banks can, but you can check by connecting to the mains outlet). 

No, there is no built-in battery in this solar panel. But it supports all the power banks charging, so that you can store power for using. 

Yes, the hunting camera comes with a solar panel with a 3m cable, the solar panel can be adjusted to suit the location and How do you get the electricity? How much capacity does the hunting camera have The product itself has a battery capacity of 7800mAh and is powered by the solar panel. Please fully charge it with the adaptor before use. You do not need to remove it often to charge it in summer and in sunny places