The canopy is just molded acetate, it really doesnt weigh much at all. Im saying stock right out of the box, with canopy, and tail ready to fly....you could add 40g to the helicopter is probably a fair estimate at what you could carry with it and still have reasonable control. Im guessing max payload is probably somewhere around 123g before it just wont fly anymore. Think one 9V battery, and the really tiny pinhole camera would probably be the most you could put on it and still be able to max performance. Anything more than that, and it would start affecting performance.

As far as the carbon blades, I think helihobby.com has them. I got mine from a company in canada, but I cant remember who or where they are. They aren't cheap though, as a matter of fact...they are downright rediculasly expensive. $50 for a set last time I checked.

If you stick with the foam ones. Cover them with clear packing tape. It will make them a little more durable.
If you are running a heavy payload, check them around the root of the blade every 10 flights or so. The foam will weaken eventually around the blade grip, especially under loads or aggresive flying. Just pop another set on and your ready to go again. Blades are pretty cheap(at least the foam ones) Normally its about 20 bucks for 6? sets of the foamy blades.