Great questions!
1. A
is still regular movement (though not a part of a move action). You cant normally move through hazards or another model's base, and stop on contact since you can no longer move directly away.
2. Mostly what causes displacement is Titans moving (Nero is a Titan, as well as a Beast):
Unstoppable : Titans can move through non-Titan models. During their activation, Titans can end a Move Action overlapping the bases of non-Titan models. If a Titan ends a Move Action overlapping the base of a non-Titan, that model is Displaced.
(Micon's Atlas Throw should be treated as a special variant of a
)
3. Step 1 of the turn structure specifically prohibits activating the model from which you are removing the fatigue. In your example Sven is no longer Fatigued after the removal, but is nevertheless unable to activate because of Step 1's restriction.
Step 1: You may remove a fatigue from a friendly Fatigued model. That model may not activate this turn.
4. Very close! You are correct that Hated does not prevent the use of tactics (favor spent by the player) which affect the Hated model. Unfortunately for Noxius, Expendable only counts him as a Zephyri model when determining whether Ludus Benefits apply (i.e. list building), and he is not a valid target for that reason.