How far can the APM-based drones fly?

is the communication all based on radio? then basically the range is limited to that of regular RC planes?

if I want to develop an Arduplane to autonomously fly to remote locations (say 10 miles away) and back (seems larger electric gliders have this range endurance ), I would have to rely on other communication medium, right? for example cellphone signals ?

Depends on where you fly as many countries won’t let you legally fly beyond visual line of sight.

However, autonomous missions have a range of as far as the vehicle can physically go on it’s power supply.
That doesn’t mean you’re telemetry link will make it that far, but that isn’t “needed” for an auto flight it’s a nice thing to have though, a bit like an fpv video link for the flight.

I’ve personally seen a quad fly about 2miles out and back without any radio, it’s only limit was the battery running out.