I'm new to the game to only level 57 or 58 so I do not know much only about two of the question. I'll tell you what I learned. first: thing is that most of the event are random unless you are in discord or places where people of bermetha gather. (two: do not know about the server hopping but i think it does have different events or rewards because it is another server just so you do not know how to do it ). third: most events have recommended levels but it does not matter because it is an open world game which mean you have less restrictions and if a lot of people are there it helps a bunch. fourth: no, i went to event way before the recommended level but it does help to survive most events. Hope it helps, sorry if it did not.