Only if it's rainbow.
I think if you choose the rainbow option you can dispense with the bow. It'd be kind of redundant. :)
I'm guessing that I don't have to wear the pony's tale...
No, you don't have to - although if you cut off Rainbow Dash's tale and wore that it WOULD be acceptable.
Where should this comment appear?
This pairing only
Whenever "Wake up covered with spiders" appears
Whenever "Have a long, luxurious pony's tail that's permanently decorated with ..." appears