No. LG Q6 Plus does not have the fingerprint scanner but it comes with advance level face recognition.
No. LG Q6 Plus comes with 1.2 A power charger which is not fast charger. But you can use Sony CP-AD2 USB charger to charge LG Q6 Plus faster.
Yes, LG Q6 Plus does have the Google Assistant.
No. You cannot change the color of the notification light in LG Q6 Plus.