Infractions/Player Communication - Infernal Tutor and Lion's Eye Diamond
There is no way to give absolute answers to some of those scenarios in a vacuum on the internet.  I agree with Hackworth's answer as far as the 'most correct' interpretation based on the rules absent any other information, but you did ask about player communication in a CREL event.  Judges are in fact required to, well, apply judgement in some situations and there is not always a 100% correct answer or 100% repeatability.

Taking scenario C, it could be:

1) Storm player is leaning forward over table looking down, holding his hand of cards, taps a swamp and puts down a Ritual and a Tutor, still leaning forward, without looking up, grabs pen with other hand to mark paper then reaches for LEDs.  Opponent says some possibly more polite version of "Haha, you forgot to explicitly retain priority, picking up the pen isn't a game action so it implies you were done casting, GG sucker."  Storm Player calls for judge.

2) Storm player puts down Ritual and Tutor, leans back in chair, puts down hand of cards, makes eye contact with opponent, then picks up pen, marks, then reaches for LEDs.  Opponent calls for judge.

As much as we'd like paper magic to be an absolute black and white game as if we were on MODO, these are different situations and some judges will treat them differently.  That's the reality of a situation that has three human participants.  (Further compounded by the fact that the judge probably didn't actually witness it personally!)  If a head judge gives you a ruling on the day-of, that is the ruling.  "Some guy on the internet said XYZ" will get you nothing but reminded not to argue with judges.