QI summon a Bansai Suzuki, Deacon Shinobi with this follower's Fanfare ability. If this follower leaves the field during my turn, do I still have to return Bansai Suzuki, Deacon Shinobi to my hand at the start of my end phase?

AYes, you do.

QIf I summon a Bansai Suzuki, Deacon Shinobi with this follower's Fanfare ability, do both "at the start of your end phase" abilities trigger at the start of my end phase?

AYes. When you proceed to your end phase, all "at the start of your end phase" abilities trigger and become pending. Then you can choose the order in which you resolve the pending abilities.

Note that even if you resolved the "return this to its owner's hand" ability first, you would still be able to summon a Bansai Suzuki, Clone Technique token.