OP...You have lots of good information here.
I hesitate to single out a particular trainer but I have a book by Julie Goodnight, Goodnight's Guide to Great Trail Riding (see her website). It covers a lot of what you are dealing with. I have ridden for many years and I find this reference handy to go back to. Right now I have a green horse and I don't want to screw up the works with her. Many of the issues you are dealing with are exact duplicates of another horse I have. Methods mentioned in this thread and in this book greatly improved the situation. Just know that some of these issues take time, patience (boy, howdy) and consistancy to correct.
Good luck to you and your horse!
If you ever find yourself in a fair fight, it's because your tactics suck. ~ Marine 1SGT J. Reifinger