Hi Brian, thanks for your extensive and competent answer!
1. I had a look at the VSL website and was very impressed by the high quality of their sound libraries (at least when listening to the demos).
I am interested in the VSL Concert Guitar. Do you know whether Notion 5 Windows 64-bit does fully support the VSL Concert Guitar with all its techniques and expressions in the Techniques panel? Is it difficult to install and control in Notion? I don't want to setup this instrument in an external user interface, as I would have to setup the instrument in the external UI again each time I open the score in Notion, which is too cumbersome and time-consuming. When I open a score, every instrument should be setup the same way as I saved it in this specific score (total recall).
I will also look at the KB article you mentioned.
2. Do you think it would be easy or difficult to create a custom VST instrument with my own expression techniques controlled from the Notion techniques panel?