That's the (in)accuracy you can expect with consumer-grade GPS.
Understanding this limitation, you just need to plan for it and avoid putting waypoints close to obstacles.
The satellites are always moving.
This animation shows what their movement is like.
The actual sats are orbiting much slower and there are many more of them.
That's not correct at all.
You would get consistency any time that your controller is...
The Mavic 2 pro is eight years old and not supported by DJI anyway.
Neither of those is true and neither would make any difference to an 8 yr old second hand drone anyway.
Not at all, except for overpaying for an old drone.