ROC-RK3328-CC - Unlisted Connectors

My RK3328 has 2 connectors on it that aren’t listed on any of the documentation i’ve been able to find so far, thought possibly someone here could help.

First: What is the Small JST style connector between the AV-Plug and the HDMI jack?
Second: What is the 3 pins mirroring the ADC0 and ADC1 connector? <Silk Screen Says PWRON GND PWREN - while I understand the abbreviations to be Power-On and Power-Enable - what do those functions do?

Also, If anyone knows. The Green LED next to the 5V power LED, does it have a pin-header somewhere, so i can route that “activity” light to outside the case?

Thanks a ton in Advance.

Does looking at the schematics help, ROC-RK3328-CC-V1.3-B.pdf - Google Drive?