1) What do you think would help improve your game development skills the most? Is a GameJam the right way and if so why?
To improve game dev skill what you need to do is game dev. So Gamejam is great way to do it cause aside you have to create a game (mostly from not-so-nothing) , you have time limit to push yourself to complete your game within time limit.
But of course, people could cheat despite the rules but it's their loss if the jam had no prize rewards.
2) Would you like to have experts at your group's "disposal" during the gamejam?
Which experts? since gamejams have time limit, I'd need experts which could make stuffs within time limit so they could be used in the submitted game.
3) What would you like to see more at a GameJam?
Well, a team of professional judges to judge and rate the submitted games. This is to get fair and unbiased rating and judgement.
4) What do you think would be the best way to make people meet people to build teams?
I don't work in team so I can't give proper answer to this.