Somehow I have managed to finish a first draft of my second YA novel tentatively titled Go West. One mistake I think I made with my first YA novel was not letting other people read it early enough in the process. I did most of my revision without getting outside input and I think I could have stream-lined my revision process by getting input earlier. Who knows?
This time I’ve asked two English teacher friends to read the first draft and give me some really general feedback. What works? What doesn’t? What are the most exciting parts of the story? Where does it drag? What do they want/need to know more about?
When do you first get feedback on your works in progress? Who do you trust/burden with this task 🙂 ?
Ideas In Things 
I usually write a first draft and revise it myself at least once (I also revise a lot as I draft). Then I see who among my writer friends might be interested in reading it — I like to get at least three reactions if I can, from people I know “get” the kinds of books I am trying to write. The questions I ask are the same sorts you list.
Good luck with GO WEST!