Once the first
Bramblewood Paragon has been applied and both of the remaining effects are applicable, the player may choose to apply whichever one they prefer, and then the remaining one will be applied afterwards. If they want to apply the effects in that order, they can do so.
For your second question, the number of counters the creature will be entering the battlefield with is recalculated every time an effect is applied. Applying the effects in the order Paragon -> Vigor -> Paragon, it goes from being:
(Creature will enter with no counters) -> (Creature will enter with one +1/+1 counter) -> (Creature will enter with two +1/+1 counters) -> (Creature will enter with three +1/+1 counters)
So it's not likely that players will choose to order these replacements in this manner, because it will result in fewer counters, but it is a possible option.
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Your third question, however, is meaningless. What is and is not “the same event” is not defined in the abstract, only in the context of what specific abilities are looking for.
For example, if you attacked with two Warriors and they dealt combat damage to your opponent,
Raiders' Spoils would see that as two separate events. (And will therefore trigger twice.) But
Pyrewild Shaman would only see it as one. (And only trigger once.) Neither of them is wrong, because there's no inherent property of the creatures dealing damage that defines how many events it “actually is”–there is only how many events a particular ability sees in it.
EDIT: Corekt speeling is importnat.
Edited Callum Milne (June 26, 2018 02:47:16 PM)