This multi-functional fill light & mobile power supply is a 2-in-1 style that can charge any device 

Absolutely, we have had ours mounted on top of our barn about 60 yards (120 feet ) and it works like a champ. Good product, very accurate. 

After the mobile phone and the device are successfully connected, as long as the device is in the WiFi area where you are connected, your mobile phone can remotely view the device data through the APP as long as it is connected to the Internet. Please pay attention to ensure that you are using 2.4GHz WiFi when connecting, and the WiFi area where the device is located has a strong signal to avoid accidental disconnection due to weak signal. Hope this information is helpful to you. 

Yes, easily. 

Yes, when you use one camera alone, just shorten the other side and fix it under the armpit, then you will have a double shoulder strap.