That is the correct spelling of "equipment" (devices, tools, or machines).
The equip spell is sent to the graveyard and the monster returns to your hand as usual :)
Yes, and in fact several Equip Spell cards would be useless if they could not, such as 'Snatch Steal' and 'Mark of the Rose'.
Yes, Equip Spell Cards target when they are activated.
No, face-down monsters cannot be equipped.
The Equip Spell card is called "Ekibyo Drakmord".
They are considered to be 'Equip Cards' but not 'Equip Spell Cards', in case anything specifies the latter.
If an Equip Spell Card is sent back to the Deck, it is no longer equipped to a monster, and therefore, the monster does not gain the benefits. If a monster equipped with an Equip Spell Card is sent back to the Deck, the Equip Spell Card is destroyed.
yes you can equip spell card cards to an opponent's monster unless the card states so a good example of this is snatch steal
No, it is a Field Spell card.
Same as when you use a regular Equip Spell card on the opponent's monster, the monster acting as an Equip Spell Card goes to your own S/T zone.
That is the correct spelling of "outfit" (to equip, or an ensemble).
Yes, but Equip cards cannot equip Spell Cards. The Z-Metal Tank will have lost its target due to the Y-Dragon Head becoming an Equip Spell card too. The end result is the Z-Metal Tank will be destroyed.