I wish to be notified on my Android phone when I get within a certain distance (few hundred m to a km, user adjustable) of a list of locations (imported in lat, long format; about 10..50 entries). Is there an app for this?
BwareArea might be what you are looking for. From the app's description:
You'll import a POI list and it'll start an always-on-top widget displaying the closest POI and alerting you if you don't follow the POI requirements. All the parameters are configurable; minimal distance to warn, allowed over-speed, whether to automatically start when your car's Bluetooth is connected, or to log your track.
Seems to fit your requirements exactly. Works on Android 4.4 (Kitkat) and up.