So I was taking out the trash the other day and I hear a drone doing a power loop and noticed it was a DJI FPV…I don’t know where it’s from but it’s within a 1/4 mile of my house, so now I’m worried what happens if I’m already flying in m mode and this person puts his up…will this mess with my flight controls on my DJI fpv at all, and if so will it come out of m mode and pause then start to return to home? Next I’m not so worried about my home built drones with the DJI air units since I fly low to the ground but still don’t want to crash because my channel was stepped on, should I be concerned with my air units too?

No this wont affect your drone,    the binding process ensures only your controller will control your drone.

My 2 mates and myself all own the dji fpv , if we all fly at the same time, 100 to 400 meter away and low to ground level ( 5 to 10 meters ) we start to lose signal to the headset goggles...
If it's just 2 of us not noticed a problem

That’s what I’m worried about, doing a dive or roll and loosing visual signal…the home built quads are under 3 meters off the ground and usually in my yard practicing my freestyle most of the time so I can just dis arm them but the dji fpv is my concern loosing visual and plowing into a house I do a lot of dives, rolls, and flips …thank god for the pause button.