Odd codes P0432 and P2000?

The P0432 is generally a bad bank 2 converter as it is the code stating the converter isn't operating as it should. I would use a scan tool to watch the upstream and downstream sensor signals to see if they are tracking each other. If they are its most likely that the converter has failed. If they are the original units, they are probably worn out simply from age and mileage. About the only time you would see O2 involvement would be if the upstream sensor was recently replaced with one that might be out of spec.

P2000 is a generic code for the same thing (NOx trap efficiency code) but isn't commonly used by the domestic built vehicles, it's something you would normally see on European spec vehicles and the ELM probably translated it that way as well. One of the hiccups with generic tools and software.

The readings you want to see for fuel trims is under about 10% combined short and long term. Closer to zero is better on both. For the O2 sensors you don't really need to follow the voltages, instead you want to see that the upstream sensor is switching rapidly as it corrects the mix, but you want the lower one to show an almost steady output in comparison, so if you were looking at a graph sensor 1 would have spikes in both directions but the downstream sensor will just have small ripples. With a bad converter the two will show very close to the same readings. So say S1 shows .8 volts, then .5 then .2 then .6 then .2 and so on, you would see sensor two mirroring those if the converter isn't functioning correctly. If you want to know a ton more about the testing you can look at Pauls' testing at https://www.youtube.com/watch?v=vyVnhCIMDnw He covers it in depth and shows the things to look at.

What you normally will see when a cat starts to wear out is that it won't trip codes all the time, it will take specific circumstances at first. Then as it continues to age the codes become more frequent until they set withing minutes. Hopefully you're at the very beginning of that stage and it won't get worse rapidly.

99.9% of the time it does. Where you will sometimes see a difference is if the downstream O2 sensor is failing and reading slow. That is why you start by looking at the O2 sensor data and seeing if the voltages are in range and if the sensors are tracking each other when the converter is up to temp. On most engines the upstream sensor is doing the work of setting the fuel mixture in the engine, it does that by telling the ECM if the exhaust is rich or lean and correcting it hundreds of times a second. The downstream sensor in most cases only tells the ECU if the cat is working, but it can also become a control sensor in the event the first one fails or in some vehicles it is used to help fine tune the fuel mix.
The system self-tests by deliberately running the fuel mix either rich or lean for a set time, then it looks at the upstream sensor response if things are okay, it then looks at the downstream sensor for it's reaction. The ECM has a table in it that it uses based on the time the test started, it knows the distance between the sensors and calculates that from the time the test starts to the time it sees the downstream sensor reacts and how far it reacts voltage wise to determine the health of the sensor and the health of the converter. That table and test is what the common trick of using anti-fouling adapters on the downstream O2 sensor attempts to fool. The ECU knows that the fuel mix goes rich, it expects the upstream sensor to go to a certain voltage in a certain amount of time. Then it next expects the exhaust to take a set time to travel the converter and next it reads the downstream sensors reactions to the same test. It knows it should take a set time for the converter to react and reduce the exhaust and that if it's doing it's job the exhaust contents should change and how long that takes in a good unit. If it sees that the times are either short or long or that the voltage change is to high or low it sets a code. If it sees that the upstream and downstream voltages are changing at very close to the same amounts and at the same times it sets the specific converter codes like the P0420, P0430 that are common.