1. Same as me in Milan in 2010. I can estimate roughly 1500 people were there
2. Q-jump is considered quite rude. Some may just look badly at you, some won't let you go and on the other hand won't have kind words for you.Take it as a "training" being some rows behind and gaining some extra rows during the moshpit (no pushing or elbows involved pls), without putting yourself in front a 1'60 m tall Muse fan.
Then aim to the barriers next time because you'll like it!
Good luck!