If you use Build Project for Device it will build a debug version. If you use the App Export Wizard... option, you can get the release version.
The .iq file that is generated is just a zip archive. If you change the file extension to .zip, you can open it up using the zip tool of your choice. Inside you should find a folder for each device that you enabled support for when configuring your project. You can determine which folder is for what device by looking at the part_number for each device in <SDK>/bin/devices.xml.
Once you know what folder to look in, locate the appropriate .prg file and copy it to the GARMIN/APPS folder on the device.