OBD II (and soon OBDIII) is a generic set of protocols. not just for Crossfires, BMW's, etc. You'll see things like O2 sensor switching (.1V-.9V rich/lean), short term and long term fuel trim, with boosted cars MGP (Manifold Gauge Pressure, similar to MAP), all kinds of things.

Once you get good at that, then you can dwell into what's called Mode 6 and Mode 9 data. This is an area where there's parameters set and you can see the actual value. In other words, you can see something that's about to break before it does, right now I believe you need factory scan tools to view this, or at the very least, factory knowledge.

As far as A/F ratios, that you cannot. You'd need some sort of 5 gas analyzer to see stoichiometric values. Some people think that O2 sensors can see this, but they're flat out wrong. O2 sensors see exactly that Oxygen, or the lack thereof in incomplete burning. Whether it's the galvanic battery type or the titania type, they cannot see unburnt HCs, NOx levels, or CO and CO2. All important indicators of cylinder head temp, misfires, A/F ratios, etc.

HTH

Justin