Hello everyone. I've been posting a bit on the forums, but i'm still pretty noob on certain content. I have a few questions on Hamlet today.

1) can I join a hamlet of a different GC? (I generally play with two other friends. two of us are maelstrom, the other is adder. can we hamlet together?)
2) do you get GC seals as a reward upon completion? or is this just for gear/anima?
3) is this 50 only content, or is it viable to bring a 40+ DoL/DoH?
4) any misc tips for a couple of people trying hamlet for the first time?