To chip in with my opinion on the diving thing. I played This is football 2004, which featured the dive option my pressing R2. This didn't work as L1, L2 and R! could all executie trick moves so an accidental slip or the press of a wrong button usually resulted in a yellow card. I did win a crucial penalty against a mate by cutting across his run and diving.
Yes, there would need to be several dive animations, yes there would need to be punishments for executing a poor dive. Many times thou on Pro Evo, when players go shoulder and shoulder, and you lose possestion, you sometimes feel ur player shouls have "gone down" to win a Free kick. Maybe a comination of buttons in the situation would result in realtisc looking dives. The same with when your knocked off balance, i.e when running at spend and avoid an opponents challege, you can opt to try and carry on your run or go down, giving a real dilema in certain situations for example a late rush into the penalty area, or when u round the GK!
Maybe a similar soprt of thing to the Square then X feint, use a quick trainge then circle to go down.
Refs should penalise thou if they feel the foul is unjust, but i believe iof they are going in include it, it should be on every game. No turning the feature off.