Am I correct in concluding that I cannot use an unarmed attack as a bonus attack, other than Flurry of Blows?
Monks get the class feature "Martial Arts: Bonus Unarmed Strike" at level 1 for an unarmed attack as a bonus action.
Unarmed attacks, despite using DEX for the to-hit and damage bonus, aren't finesse attacks and can't use Sneak Attack?
Yes. Sneak Attack requires a finesse weapon.
Unarmed attacks can't dual wield?
You're not even "mono"-wielding. You're zero-wielding. Of course you're not dual wielding.