I tried this, LOVO, on the recommendation, and I must say, it was profound to hear my stuff read like that by someone other than me. I have to admit, it sounded pretty good.
To the first question...yes. To the second question...no. Recently wrote 2 shorts stories, both around 8k words and I am working on two novels. All fiction, though I wrote some pretty good stuff in grad school that was entirely non-fiction on colonial America.
I am going to dissent a little. Personally. I don't think you need to get too far in the weeds with a magic system. Too much detail on the physics or numerology of magic systems and you endanger your story. I prefer, there is magic, some can use it and some can't, you build up strength with...
The summary is one part book summary and one part sales pitch. You want to say, this is what it's about, and you want to convey, this is why you want to read it. I would pick #4 actually and stop at bullet 5 use the last bullet as your tag line.
I had to embrace the idea that a rough draft is by definition rough and put aside that I was going to produce a perfect draft from the very start. Once I learned that idea, my writing got easier, because I didn't worry about every little oops.
Word counts are something you have to become...
Aspiring writer of day dreams. Been scribbling things down since I was a teenager way back in the 70s. I'll let you do the math. Retired Soldier, Engineer and renaissance man. I look forward to seeing what everyone does and hopefully you see what I do and helping me get on the track to some...