Finale can export WAV, MP3 and Midi files. Which file type does Sonar take and once I've imported the tracks, do I have to select the TSS library to play it back, providing I don't have the Aria play mapped to Sonar?

Wav and mp3 are audio formats. Both can be imported into SONAR. Of the two, wav would be the best to use because it is not a lossy compressed format. MIDI is not an audio format. It can be imported into SONAR but requires assignment of softsynths to play the MIDI informaiton.

The TTS-1 is a General MIDI synth and so the sound mappings should be similar. 

thank you for the tips. I purchased Sonar in 2009 but just finally learned how to map Tutorial one so I can hear something. I've getting tired of using Audacity so I'm moving up. Do you have any recipes that you follow to really make these WAV files should really good. I'm still trying to figure a process that seems to yield the best results.