Hi!
Reply was provided in another thread, but will repeat it here.
Raindeers will be unbounded with a server re-start.
Brown Raindeer in the shop is different from the Brown Raindeer in the box; so the Raindeer will not be removed from the shop. The armor that is coming in the box with Brown Raindeer can be used on the Brown Raindeer from the box only, not on the one from the shop.
Each Brown Raindeer has it's own advantage - the one from shop is faster; the one from box can be equipped with items from the box, so looks a bit prettier.