Note re: turn by turn directions and the 500.
it can do turn directions using the tcx file downloaded from sites such as ridewithgps.com
I've been using this on my La Bella Preme training rides with team as I am leading the rides and am not 100% familiar with area we are riding in. Someone else designs route. I save route to my ridewithgps profile. Download the tcx file to my computer then transfer file to Garmin 500 using directions provided. It works pretty well.