I am pretty happy with the rules as they stand
Ive never seen the interpenetration abuse happen, so can really comment on that, but it sounds a bit of a bummer. Niks FOGR solution does (I think) prevent HYW billmen passing through the LB. not that I have ever done that on purpose, so no big loss.
the turn 90 / move thing is probably the nastiest thing that drilled armies can do, so I can see the argument for getting shot of it, or reducing it effect. Half move sounds sensible, though I fear it would half my fun
1 AP for fleeing off table is a pain in the fundament, so just make it 2. the 'steppe nomads win that way' argument if great for scenarios/campaigns, but silly in a one off battle.
Maybe adjustments should be in a forth coming tournaments supplement (to go alongside the the campaign supplement)