The cold smoke attachment is a cardboard box type improvised. Bradly, as I know, does not make a attachment, maybe some else does I never seen one. You take the smoking unit off the box, attach to a cardboard box, buy aluminum cloths dryer venting. Attach the dryer vent from cardboard box to Bradly, maybe 4-6' away.
As for size, the standard one is not very big as other commented. They have a stainless larger one, might be worth the extra hundred failing buck.
The original size, well you will have a hard time getting a turkey in there. Last batch of sausage I put in there was 10 lbs, that was to much for the smoker. You do not want sausage to touch while smoking. 5-6 lbs might fit in there ok. Ham, well it would have to be cut in half and maybe it might fit?