Use of external Power supply and triggering output to a relay

Hey all. 2 questions:
a. Can I power the device with an external power source/USB?
If so, does it have a connector/pins for that?
b. Can i control output pins/GPIO to trigger a relay, for example, to open the garage or electric lock?


Yes you can. Please see for details. Please note that your power source must supply 1.8 V to 3.3 V, i.e. you cannot use USB as-is.