...does that mean I should NOT convert a wav file once it's already imported? Or should make sure the wav file I'm importing is the proper sample/bit rate, then create a brand new project, THEN import the proper wav file?
Neither. There is no way to convert a wav file in-place once it's already imported. It is not necessary to convert a wav file prior to importing, as SONAR will automatically convert it to whatever format the project is set at.