Assuming an eTrex with a memory card: Yes for the map file, no for the track.
The map file must be named gmapsupp.img, and in a folder named Garmin.
There's no way of sending tracks/routes/waypoints to the eTrex in mass storage mode (well, you could copy them to the memory card, but it won't see them).
To transfer these you must have the eTrex connected in normal USB/Garmin mode (not mass storage), then send them using something that uses the Garmin protocol. eg Mapsource, GPSBabel or Garmin Communicator plugin etc would work.