And the winner is - Mit again.
And the answer is:-
1. Air deflection thingi just ahead of and below the leading edge of the horizontal tail plain.
2. On a Piper Cub.
3. I had in mind ZK-PSC - but as Mit pointed out - ZK-BRO has the same.
Another mod on a Cub that I have not seen for many a year is the cable across the undercarriage.
Again on ZK-PSC.