Not a football official, but I like to think I know the rules.
I look forward to the rest of the discussion in the thread.
#1. Penalty should be applied on the succeeding kickoff, I guess (???). (Rule 10, Art. 5) However, I freely admit I have no idea how halftime plays into this. (Sidebar: if it was an unsportsmanlike conduct personal foul, say, for fighting, is it enforced the same, i.e. after the half?)
#2. Incomplete. (NCAA AR 7-3-6 XIII)
#3. I personally don't have KCI here, but definitely targeting. Eject. (Forcible contact to head or neck of defenseless opponent; clearly the returner meets the qualifications of 2.14.d)
#4. We don't have a great angle here, but it doesn't look like the entire ball crosses the plane of the goal line. Touchback.