I cannot answer your question but I believe that the Havas bus only goes to the domestic terminal so if you are going for an international flight there will be a walk between terminals involved.
See...
http://www.havas.net/en/shuttle-parking/dalaman/"Fethiye
Airport: Shuttle is available for all domestic aircraft landing at Dalaman Airport.
Bus terminal: Our shuttles are arranged according to aircraft departure times. Our shuttles depart from the intercity bus terminal 2.5 hours before aircraft departure times."
Maybe others can provide information based upon experience. I have taken a bus from Kalkan to Dalaman (via Fetiyeh and sometimes involves a change), but the endpoint is the Dalaman Otogar and you have to get a taxi to the terminal (about 25 lira I believe). Benefit of the stop off in Dalaman is that you can get a good meal at a reasonable price before getting to the airport, but overall transfer is more like three hours.
Mark