For your first two questions, I'll refer you to our book Bulletproof, chapters 9, 3, and 5 respectively). I've also commented on your first question in response to other posts in this discussion. Have a look, see if it's helpful.
Re: your third question, I probably struggle more with the environment than with writing itself. I generally look forward to the work of writing. I love working with my partner and I love sitting in a room alone and doing the work. That doesn't mean every day's a good one or that it always comes easy, but I love the work. What's hard is grappling with how random the business can sometime seem. It's important to be able to distinguish between your circumstances and who you are as a person. If your scripts are landing, that doesn't necessarily mean you're more talented than if they're not...and it certainly doesn't mean you're a better person. If you listen to the most successful people in the business talk about their careers they will each, to a person, mention how difficult the struggle was to make even their best, most impactful movies. So not personalizing that, not allowing the challenges and obstacles, all the external stuff, to adversely impact relationships and self-esteem, and the ability to keep moving forward, is no small thing, and it's critical to maintaining equilibrium over the long haul.
We included our original outline for the first act of The Family Man in chapter 5 of our book. The whole chapter, Building a Bulletproof Outline, deals with what goes into a useful and effective outline and why these elements are important. Maybe you can use the "Look Inside" feature on Amazon and see if it's helpful...?
I didn't learn from the books, I learned from reading screenplays (hundreds of them, as a reader for producers and studios) and writing them, perhaps as many as a dozen before my writing partner and I actually started selling them. I didn't look at the books, for the most part, until we decided to write one of our own, based on our experience and essentially written to our younger selves--the kind of resource/companion we wished we'd had when we were coming up. My impression: most have something to offer, but special attention should be paid to those written by people who've actually written within the world you aspire to enter. So if you want to write studio movies, read Save the Cat, and the Lennon and Garant book, and I truly hope ours has something to offer as well. Bottom line: take whatever wisdom and insight and practical tips you can from wherever you find most helpful and be very skeptical of, and probably completely ignore, all the rest! No one can guarantee you success, be very wary of anyone who does, but with persistence and resilience, you may be able to get there with a little help from those who've come before...Good luck!