first: THANK YOU for linking to videos in your post. i really appreciate that, and it makes it a LOT easier to diagnose.
for 1 – i agree with you. i think she’s focusing on the “prey” with her odd head movement. i’ve seen this before in a healthy cat.
for 2 – maybe? i’d wait and see on it, honestly. if this is only during walks and play it may be behavior-related rather than health.
If the ear is that bad you need to see a vet for medication.