VO Recording in Audition - effects & gain don't seem to change live recording

Sorry, no - incorrect, and it's by design. It has always been good practice to record dry; if you apply effects to a recording as it's recorded there's no way to undo this if you change your mind. What happens in Multitrack is that you can apply effects to your track, and you'll hear them in the monitoring, but if you remove them after you've stopped, you'll be left with the unaffected track. If you don't remove them, then obviously they will still be applied to your recording.

Gain setting is not an Audition function - Audition records exactly what it's sent from your sound device - very reliably. If you are recording a mic, it's normal not to let the audio get to over -12dB, and you have to adjust your mic input stage to achieve this. The space between -12 and 0dB is called 'headroom' and you would be expected to adjust the final level using Normalize. The purpose of headroom is to allow for unexpected peaks. If you're using compression in the form of a limiter, there's a little more to it - you have to normalize twice to get the levels correct. First you normalize the raw recording to 0dB. You do this because that's the value that all the compressor controls relate to. When you've finished applying your limiting, then you have to normalize again to get your peak level back to a more sensible value. For instance, if you flattened the top 9dB off (this is quite a normal amount) then your signal would be at -9dB afterwards, and you'd need to renormalise back to just below 0dB to take advantage of the raised levels.