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Well, my opinion of a tune up on a modern car is all the things you've already mentioned, plus any other consumable items, like filters and fluids. The things you mention are all ignition related, but don't forget something as small as adjusting tire pressures. I would say all the fluids, including brake and trans, coolant and engine oil, their associated filters (if any), the accessory drive belt (if needed), chassis and suspension lube, wiper blades, stuff like that.
Older cars got a "real" tune up. When I do my 1973 Triumph, it's an all day affair. All the stuff above, plus points, adjusting the timing, adjusting the carb mixtures, syncronizing the carbs, adjusting the valve tappet clearances, etc..
If the noise in your catalytic converter is internal, then I would say the catalyst "brick" has started to degrade within the shell and pieces of it have broken off and are bouncing around in there. This has happened to two cars I've owned, and the noise it makes can be really annoying. However, your saying that the noise is outside the shell, which leads me to believe that the heat shield may have broken loose from the cat itself, and is clanging and bouncing around a bit. These heat shields are held to the cat body by a few small spot welds, and the spot welds tend to rust faster than the rest of the shield, causing them to occasionally break loose. This has also happened to me on a past vehicle. Short term solution is to take a pair of metal shears and cut the heat shielding off the cat. Be careful though, depending on the design and placement of the cat, and the amount of clearance between the cat and the floor, things may get a bit warmer than normal in the floor pan area directly above the cat. I've removed the shield with no ill effects, but I can't say that would be the case with every car.
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