Radar...I would kill inflight radar. Have a tower guy vectoring. If I have to have one, I would ask to have it ranged. Only targets in range show.
With regards to sector counters....Well, absolutely no for flights under 300ft AGL. But I would go further. I would like to replace the current scheme. Instead of the actual number counters I would use a single dot when enemies are in excess of, say, 20 (maybe 10 or 15, that would be a matter for fine tuning) regardless their Air, Ground or Sea condition, and nothing otherwise. Enough to give you a clue where the action is (gameplay), but not enough to ruin a surprise attack. Just to give notice that something is happening in that sector.
Cheers,
Pepe