0) chemistry
1) had to negotiate to be recognized correctly as inventor on patents for my own ideas, to be included in important meetings, to be allowed to publish work that might have been held as trade secrets, to have appropriate technicians and lab space, for travel to professional conferences and workshops, not to travel to BS things I didn't want to go to that the sales or marketing guys thought I should ship out for, for new office space, for a better computer, for administrative help, for vacation days, for comp time after working some crazy hours, for coming back to work part time after child birth . . . it goes on and on.
2) none of the above were easy, but they were all easier than I thought they would be beforehand.
3) yes, because I watched as a spectator while male colleagues and subordinates (or prospective employees) were handed higher pay and other extras that they didn't even ask for, while other female employees in the same positions were paid less right off of the bat, offered less in general all of the time, and then blamed in various ways when they asked about it. There have been too many published studies to count about this, and I witnessed it on a daily basis once I got into a position to see who was being offered what (prior to even a negotiation beginning.) Women in STEM, for the most part, get screwed out of fair pay, fair perks, and fair shares of the workload. Doing more work for less pay is more common than not to this day.
4) Yes, one in college and then another one that was really valuable because I could apply the principles right away a few years into my career. I've also read several books.
5) I am not longer afraid to ask . . . for even stuff that seems ridiculous to me. I also am very aware of thinking about win-win scenarios, having my ducks in a row through research prior to asking, gauging tenor and timing of discussions, and making a long list of negotiables to work with. FU money helps A LOT, and I have it but I'm not afraid to ask for more of it.
6) Diplomacy and frequency of requests, although I do my best to stay relentlessly pleasant.
There is still clearly a bias that I should be making less than men, and frankly it pisses me off, so I have to work very hard to mask it. One time I negotiated a substantial raise for myself based upon merit, and then I later I learned that at the time I got it there was an immediate objection from the level above that they couldn't pay me more than my (much, much lower performing) male colleague who was in their boys club. So they matched his pay, and that of all of the men paid less than me even at two ranks below me, up to mine even though they didn't know about my pay increase or ask about their own pay increases. Then one specific low performer went out and got a competitive offer and they raised his pay again to keep him and didn't raise mine to match. Trust me, I'm doing the same thing shortly, but it gets old. It never ends. Basically, it's okay where I work to pay women the least, but it's not ever okay to pay a man the least.