QIf I search my deck with this follower's Fanfare ability, do I still have to reveal the card I searched for?

ANo. Whenever instructed to search for a card with specific features, you have to reveal it to prove that it meets the conditions specified. However, since this follower's Fanfare ability does not specify the kind of card, you don't have to reveal it.

QWhen playing this follower's Fanfare ability, can I choose not to add a card to my hand?

ANo. Whenever instructed to search for a card, if the only condition specified is the number of cards, you must find that number of cards. Since this follower's Fanfare ability specifies to search your deck for any card, if your deck has at least 1 card you must search for 1 and add it to your hand.