Yes, LG Q6 Plus does have the Corning Gorilla Glass.
No. LG Q6 Plus is not a water-resistant phone but it is made of incredibly strong 7000 series aluminium.
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 G6 Plus does have the NFC sensor.