https://www.thehelicopterstudyguide.com/how-does-a-helicopter-perform-in-ground-effect-vs-out-of-ground-effect/
The positive effects of IGE hover vary from helicopter to helicopter and are, as we have discussed, also dependent on DA, helicopter weight, wind direction and speed, etc.
There are many different rotor and tail rotor designs so IGE hover decrease in power required advantages vary. I don't have my old NATOPS manual handy but in the SH-60 I think the IGE gave you 2-3% increase in efficiency.
3 "Would the ground effect that gives additional lift, not also require more anti torque eg the rotor has more grip on the air, so the reverse torqe on the fuselage increases?
No. Any reduction in power required, a benefit of IGE hover, reduces, in the broad sense, anti-torque requirements.
4 Would that same thing, the ground effect, at the same time make the tail rotor more effective, or could there be a scenario that the tail is so long , out over the edge and the ground effect just vanishes there.
Again, different designs, combinations of main and tail rotor criteria (blade cord, type of tail rotor, etc.) can have varying degrees on efficiency IGE. Many books have been written.
The 60 tail rotor, for instance, is canted and helps with anti-torque efficiency in certain flight profiles:
So is the 53E:
But if you look closely you can see the difference.
The Huey in the video does not have a canted tail rotor.
All of that said, the tail rotor doesn't "see" IGE, all the machine knows is that less power is required across the spectrum.