No. You cannot change the color of the notification light in LG Q6 Plus.
Yes, LG Q6 Plus does support OTG.
No. LG Q6 Plus does have the LED notification light and it also has the Always-On display.
LG Q6 Plus has 3000 mAh Li-Ion battery which offers talk time of about 16 hours and standby time of about 200 hours.
LG Q6 Plus SAR value is as follows:
SAR Value (Head): 0.72 Wkg@1g
SAR Value (Body): 0.455 Wkg@1g