RRG wrote in another thread that Ywains ability that makes an opponent suffer a
result is reduced by armour, because all damage that comes from a damage tree result of some kind is reduced by armour. The only damage that is not reduced by armour is the damage that is just described as a text, like "suffers 3 damage". (
viewtopic.php?f=4&t=34004)
So I agree that you should only rarely be able to do damage with Ambush, such as when you are ambushing an armour 0 model.
As for extra successes, it would obviously work if it just said "resolve one success". But it doesn't, it says "resolve one net success". "Net", as the dictionary tells me, means something like "final, after all subtractions and deductions".
So I still feel like the only possible reason for RRG to put the word "net" into the rule is to say that the final number of successes you will achieve is always one. Allllways.
If you push the enemy into another model, normally that would modify your number of successes by plus one. But the word "net" means "the final number will always be one, no matter how much you try to modify it before you reach that final".
So I really don't see how you can reconcile the meaning of "net" with the idea that you can count the plus one success from pushing.