Releasing through a major label could also involve various promotion fees, like advertising, radio airplay, photo shoots, music videos etc, so there are most definitely costs outside of production and distribution, meaning EDM doesn't necessarily get off easy. Labels might also have dedicated in-house mastering so all their stuff sounds consistent, and that could come out of your advance too.

Practically everyone, to be quite frank. This is standard operating procedure in the music industry. Every single part of the release that you cannot personally provide, from the songwriting to the mixing/mastering to the cover art, is money that the record label will have to spend on you.

This is the truest thing. A label wants you to be the complete package. Less work for them? Good, big labels are crazy busy. It's all about how much you can do for them, so maybe dabble in graphics and marketing and start learning things over time. You can do a lot for yourself. I was able to gain over 30,000 yt followers from strictly internet marketing when I was 15 y/o making videos about video games.

In short I wouldn't jump the gun and go w this label early on.