I'm glad to hear you've decided to proceed with the cardiac cath...it truly is the best way to know for sure what's going on.
The last I knew, my cardiologist at Mayo Clinic swears by the Cypher drug-eluting stent, from his personal experience and studies he's familiar with. I didn't have the chance to research the options until after I had one, as I had a 99% blockage. I've had mine almost 2 years, and have had no problems. A repeat cardiac cath was done almost 14 mos after placement, and the artery was as clean and clear as the day he placed it.
I do know there is good data to support that the drug eluting stents reduce the restenosis (blockage) rate from almost 30% to less than 10%, probably less than 5%. There is some data (though perhaps not very good data) to suggest there is a higher thrombosis rate, especially in the first 30 days, with the drug coated rather than bare metal stents, but if you take your Plavix and aspirin this shouldn't be much of a problem.
If your cardiologist prefers to use bare metal stents, I'd want to know why, as my belief is that the drug eluting kind are the "standard of care" these days.
As for how long they last, they are made of stainless steel, if my memory serves me correctly, so theoretically they should last forever....though that is a question I quite frankly haven't had the nerve to ask my cardiologist (and haven't happened upon any research that actually discusses it). I do know he told me if it ever closed up, he should be able to just thread another one through there and "layer" them in.
Hope this helps. Good luck, and hang in there!!! With luck, you will have no blockage, or only a minor one that can be treated with medication, diet, and exercise.