I'm not quite sure what the question(s) is/are, I admit to getting a little lost while reading your post. I'll start with something simple and then we can go from there.
In the past, when I have wanted to record a solo piano piece using Pianoteq, I simply plugged my piano into my computer with a USB cable to send the MIDI notes from the piano to the computer. I also plugged some headphones in so I could listen while I played. I recorded a MIDI file of my performance right on Pianoteq, using the piano sound I wanted, and when I was satisfied with my performance, I took my best take and exported it as an audio file. That seems simplest and also best in terms of audio quality. If I still wanted to mess around with the audio file (normalize, compression, eq, reverb, whatever), then I used something like Audacity or GarageBand for that.
The stuff you're talking about seems to add a lot of other steps. I'm guessing that for some specific purposes that can't be achieved by the method I describe above, but I'm not clear on what those purposes are. Can you elaborate for me?