I think that is a culmination of high crit chance, GA and masterworked, also maybe they are useing a GF.
Well basicly yes. Mendeln now works in a pretty weird way. It’s base damage is still YOUR base damage, and than multiplied by anything that mutiplies minion damage. That is why if you look at Kripparian’s video explaination(https://www.youtube.com/watch?v=CovYs-TkAHk&t=305s&ab_channel=Kripparrian
), he shows that minion damage is a couple hundred, but Mendeln procs are 50k.
Oh no keep them, those are fine, you still need some, they are helpful and can stack them up to then get multipled, it’s just doesn’t realy worth it to have them on your items, as you can have more valueable affixes there.