I'v not played against flyers yet but i considered a dakka jet for my orks, i found my self really struggling to see how i'd eep it effective with how they move, they really are tricky when you think about it.
Also you have flak cannons you can buy as terrain, tide you over until new books which will blantantly be laden with the new spec rules, including skyfire and flakk missiles and all sorts
Plus you also have reserve roll debuffs etc.
Close combat, no retreat is gone, vehicles are now waffer thin so dont present much of a prob and in CC you smash them.. Kharn is now (i think) the best anti tank unit in the game right now.
Jump troops became better and although the random charge averages 7, fleet now really buffs this with a re-roll on 'either' dice, huge.