Some great questions. I am not an expert but here are my thoughts
This is where I kindly share that you are wrong on the first two accounts.
1.
Catapult discards from play. Air Power cited the rule book above.
2.
Swept Away kicks in and prevents the death. There is only one thing in this game that happens simultaneously: assignments. While assigning each minion happens in a particular order, the second the assignments are set everything happens concurrently (thus allowing a card like
Southron Chieftain to take effect even if he is the "last minion assigned").
Another way to look at this is the classic wound prevention with
Armor. A damage+1 minion would only place one wound if
Boromir, Lord of Gondor is wearing
Armor. This makes sense. But if you have Gandalf and try to prevent that wound with
Intimidate, the first wound would be prevented, but the second wound (the damage+ wound) would then be applied to Boromir.
Armor does not negate the damage bonus, it only says that a character can max out at one wound per skirmish phase.
3. Sam could take the ring with his response action, and then Gollum would add a burden. Check out
this other conversation on response actions and order of events here.
Cheers.
-wtk