Invulnerability and Green Goblin Global

Lets say i use Invulnerability on my turn
My attacking characters that get knocked out this turn return to the field
I then attack with a sidekick character
My opponent Declare Blockers
Then i use Green Goblin Osborne Global to knock out my sidekick to deal 2 damage to a character
Will my sidekick return to the field? If so, can i target the same sidekick again?
Also, if this sidekick is blocked, i am guessing he won't deal his damage to the blocker?
If he is unblocked, no damage neither?
My attacking characters that get knocked out this turn return to the field
I then attack with a sidekick character
My opponent Declare Blockers
Then i use Green Goblin Osborne Global to knock out my sidekick to deal 2 damage to a character
Will my sidekick return to the field? If so, can i target the same sidekick again?
Also, if this sidekick is blocked, i am guessing he won't deal his damage to the blocker?
If he is unblocked, no damage neither?