If I use Ready to make an attack with a reaction, can I also take an associated bonus action e.g. Flury of Blows?

Can a Monk use a quarterstaff 2-handed and get a bonus unarmed strike?

Can a monk use a quarterstaff 2-handed and get a bonus unarmed strike? also, does the unarmed strike add dexterity mod to dmg?

Does Sentinel happen BEFORE or AFTER resolving the triggering attack?

What’s the sense in giving a Demilich 80 HP making it vulnerable to Power word kill?