Yes, LG Q6 Plus does support Miracast.
No. LG Q6 Plus does have the LED notification light and it also has the Always-On display.
LG Q6 Plus has 5.5 Inch Full HD+ FullVision display which offers 493 PPI display resolution. LG G6 Plus also has Corning Gorilla Glass protection.
Yes, LG Q6 Plus does have the FM Radio.