Questions about Icy Box ICYBOX IB-HUB1409-U3 4x Port USB 3.0 Hub, Black

Depends on the charging current. The USB plug must be plugged into a port that supports at least 3 amps. For pure charging, an adapter with 4 outputs is much better.... (also better for your Apple) eg: Ugreen fast charger (65 W)

There is a small green LED between the label/connector and the first USB port. However, I did not notice it until just now/it is not obtrusive.

The transfer between laptop and external hard drive works perfectly. However, I have only connected one external hard drive.

Yes.