Hey Dan,
On the two-staged one pictured I used 2 chutes. The camera was recovered on a 16", 8 shroud line nylon chute, the booster on an Estes plastic 18" chute with the meatball cut out of the center. This gave both parts a nice gentle recovery. I would not use the stock Quest paracute for the camera section by any means!
Yes!!! Make sure you strengthen that little cardboard disc where the shock cord attaches!!!! I would actually try to put a 3/32" hard plywood disc in its place.
Lastly, can you make the camera assembly slide into the payload section from the top, then line it up with a hole under the mirror hood? This way you can glue the bottom coupler on and use a strip of vinyl tape on the outside of the nose cone body tube joint to hold it in place. Sort of the way the Estes Cineroc went together. I have attached a picture of my 35mm Quest tube camera assembly. It did not use a mirror hood but it slides in the tube like I described.