Hey, you were not "dumb", just learning a new set of rules.
And, for me, personally, I don't thing "goofing something up" is very important. Again. if all have fun, mistakes are not too important.
"it didn't seem that 3-5 stress was 'running hot' at the time. maybe that's just our mistake.)"
One thing that players get used to, a bit meta, is to try and rest now and then to drop 1 or 2 stress.
Also, often, the GM will give moments to drop stress (to change rhythms etc.).
I would say 3 stress is kind of okay, but 4+ is a bit touchy (you have a 50% chance of getting a panic result on a panic roll).
re. Scream and when to trigger the panic-- it is not clearly specified, to me, when that happens.
I believe this depends on what triggered the panic roll.
If it is on the player's turn, then it happens in their init' in the round.
But some actions state that "you must make an immediate Panic Roll". For me, in that case, the scream would start at that moment, and raise others' Stress level-- and then you lose your Slow action when your init arrives.
My take on this is that both possibilities you gave are possible.
For your other question (re. Scream / Flee) there is a rule on p. 104:
PANIC ACTIONS: If you roll a 10 or higher on your Panic Roll, you will be forced to perform a specific action. If the Panic Roll was the
result of a skill check for an action, the action is cancelled and immediately replaced by the forced panic action, even if you rolled a 6.
So that rule means that you lose the actions (even if Flee is fast etc.).
Otherwise, for Scream etc., it seems pretty clear to me that you lose your slow action (and replace it by Scream), so I read it as "yes, you would spend THAT action screaming, thus clearing the effect".
Playing in France, and online