Appreciate the info, but FYI it's a little confusing.
As for some of your issues, they have nothing to do with FM. The process for connecting at PVG is awful, but that's more of poor layout, and Chinese regulations issue.
As for PreCheck you could have DL reissue your BP. They just can't do the initial checking.
Yes you could use AG/KLM lounge as STE+. MU/FM use Thai because of old contract that predates FM being part of Skyteam.