Regarding the Baro vs Radio, here is the deal:When performing ILS approaches, the charts will give you a DH in feet above threshold elevation. To set up for this, you switch to radio and set it to the documented decision height (usually ~200 feet).When performing VOR or LDA approaches, you get an MDA (Minimum Descent Altitude) instead of a DH, which is a BARO altitude (MSL) you should not descend below unless you have a visual on the runway. So when flying a VOR approach (for example), you set the knob to BARO and punch in the required MDA. This will give you the "Minimums" callout at MDA, and you can then land or go around as required.Hope that clears this up._O.K._