Mark, everything you say makes sense. But remember that when you produce sound, you are hearing internally and externally, and this is not the same as a voice teacher will hear. Only he/she could indicate when the sound is correctly emitted, when there is a lack of breath support, when there is an excessive vibrato, and when it is plain wonderful (ha!, they never say that!).

Then, messing around or working in an organized way only by yourself, will lead you to no place. Not even the best tape recorder is of any help, because what you will hear will be very, very far from reality and will probably be too discouraging.

Moreover, the teacher will sing for you and show you amazing things. Don't care about the style which may be not what you want, just concentrate in the quality and safety of the emission. My teacher (a professional tenor) used to demonstrate the use of the cavity below the diaphragm just by taking my hands and putting them on his belly and back. It was a little embarrasing and I didn't like it very much, but then I realised what he was talking about: this guy was equipped with air bags ! I did never reach that phenomenal achievement, but improved a lot and could do a similar demonstration, to my wife only.

Un abrazo - Andrés