You really aren't going to be able to tell much about the age of the timing belt with a visual inspection - unless it has started to come apart already which means you're going to have to replace it immediately. My experience has been that a used timing belt looks pretty similar to a new timing belt, and there's no way to know whether the one on your vehicle has 5000 miles or 50,000 miles on it.

The butterfly valve problem originates when the bushings that support the butterfly valve shaft wear out, allowing the shaft to move around and vibrate. This vibration and movement allows the screws holding the butterfly valves to the shaft to possibly loosen and eventually come out, dropping into your intake, along with the valve itself eventually. You can check to see if your shaft has any play in it - you'll have to remove the bracket above the thermostat housing to see it. Get a screwdriver down in there and see if you can move the shaft up and down or side to side - if you can then you need to replace your lower manifold assembly. Not only is there a possibility of the butterfly valves coming loose, but you'll have a vacuum leak also that can affect how your engine runs.

Looking at the front of the lower intake manifold with the bracket removed - the actuator moves the actuator rod which moves the bellcrank on the end of the shaft.


Another view from the side - you're looking for the white spacer behind the bellcrank, that's the end of the shaft.


Another view, lower manifold assembly off the vehicle.