Yes
Yes
Yes
Yes
No they do not.
Yes
I have a 97 Impreza, and it should have 3 catalytic converters, but I took one off, and never put it back on, and my car runs just fine, so my answer is don't worry about it.
Yes, if it came from the factory with a converter.
Catalytic converters do not rattle. If it does it will need to be replaced as it may block the exhaust. Loose heat shield?
Crawl under your Kia and count them.
Cause on that car there is two converters filtering each different kind of elements. You need both of them to comply with the legislation.
Catalytic converters are failing and need replacement.
Cars did not get catalytic converters until 74. Trucks were 81, or 82.
Catalytic Converters are required in every state and city in the United States including American Fork, Utah. It is illegal to remove them.
There are no differences. High flow catalytic converters are not really high flow; the catalytic converters you have on your vehicle are as high flow as you need them to be. A "high" flow converter will either be of a larger diameter, or the inside is made in such a way that there is less restriction to exhaust flow.