Mogis's Warhound

Unlike other Auras, an Aura with bestow isn't put into its owner's graveyard if it becomes unattached. Rather, the effect making it an Aura ends, it loses enchant creature, and it remains on the battlefield as an enchantment creature. It can attack (and its {T} abilities can be activated, if it has any) on the turn it becomes unattached if it's been under your control continuously, even as an Aura, since your most recent turn began.

You still control the Aura, even if it's enchanting a creature controlled by another player.

If a permanent with bestow enters the battlefield by any method other than being cast, it will be an enchantment creature. You can't choose to pay the bestow cost and have it become an Aura.

On the stack, a spell with bestow is either a creature spell or an Aura spell. It's never both, although it's an enchantment spell in either case.

If, during your declare attackers step, Mogis's Warhound (or the creature it enchants) is tapped, is affected by a spell or ability that says it can't attack, or hasn't been under its controller's control continuously since the turn began (and doesn't have haste), then it doesn't attack. If there's a cost associated with having a creature attack, its controller isn't forced to pay that cost, so it doesn't have to attack in that case either.

If the enchanted creature leaves the battlefield, the Aura stops being an Aura and remains on the battlefield. Control of that permanent doesn't change; you'll control the resulting enchantment creature.