QIf I return a token to hand with this follower's Fanfare ability, does the token count toward the number of cards in my hand?

ANo. Tokens are removed from the game immediately after moving to any zone other than the field or EX area.

QIf I return Harvest Festival to hand with this follower's Fanfare ability, can I draw a card with Harvest Festival's ability before giving this follower +X/+X?

ANo. You finish resolving this follower's Fanfare ability before playing Harvest Festival's ability.

QIf I select 0 cards to return to hand, do I still give this follower +X/+X based on the number of cards already in my hand?

AYes, you do.

QIf I already have 5 cards on my field, can I play this follower, return some cards to hand with its Fanfare ability, then put it onto my field?

ANo. A card's Fanfare ability triggers when the card is put onto the field. Since your field is full, you can't put this follower onto your field, and therefore can't play its Fanfare ability.

QCan I return this follower to hand with its own Fanfare ability?

AYes, you can. In that case, you would simply not perform the remainder of the Fanfare ability (giving this follower +X/+X).