Thank you for the feedback! I have filed your requests, and updated existing requests so that our Development team can review everything!
In regards to showing all maps in a collection, the overview map in the upper left corner does display all of the maps that you have in that collection. Unfortunately, we cannot display multiple maps in the map view at this time, but the overview map gives a sense of what maps you have as well as shows your current location.
For the GPS receiver, it’s possible that the receiver was not feeding the information correctly to your device. AM works by just tapping into whatever GPS information the phone delivers. If the GPS receiver is not connecting correctly, or the phone is not giving the information to our app, this can cause problems. We have tested with Garmin devices, and have found them to work very well. If you are still experiencing this issue, can you let me know what Android device you are using, as well as the exact Garmin device?