For #5 - doesn't it clearly say that AFTER the tribulations the Lord comes and gathers His people form the 4 winds? Or is that from heaven, - as in - we'll be in heaven already?
Not sure, but maybe the sun being darkened and moon not giving light is the church falling and the stars being the people of the church being killed / taken by the enemy...etc... Then the powers of the heavens being shaken is God answering that blood and sacrifice by doing some huge, supernatural things.
I heard angels will be more often giving assistance visibly.