About item 4, in the old days of L2, some skills had in description "Over-hit" for example Solar Spark from Spellsinger, all over-hit skills gave extra xp/sp as I remember. But tbh my first official server is this one, L2 NA Classic, Ive mostly played illegal servers until recently. Maybe there are players from Live here that can argue if this is not true. Now I dont even know if overhit skills exist.
If you are completionist, good luck completing all Collections!
And about fishing, no idea, never enjoyed fishing.
LE: I just checked and my trickster's Twin Shot has Over-hit in the description text.