Is it more advisable to install keyboard synthesizer software (driver, voice editor, VST extensions, etc.) on the computer before or after installing SONAR? Or should it make no difference either way?
 
Thanks!

Seeing as part of the installation is a plugin I'd say it's better to install Sonar first. But either way it won't make any real difference. The only connection between Sonar and other music type things is likely to be a plugin.
All Sonar needs to know is where you put your plugins by default.

Hope that helps.

doesnt matter - what if u dont have a MIDI controller yet?   its fine.