Such good comments so far.

I agree, do NOT send this note--but I would like to add, even if you do have another job lined up. I expect your GM would feel defensive at your appraisals of how things are going. If he really understood, I submit he'd probably be doing a lot of that already. The fact is, a great many managers, including in the U.S. and including people with MBA degrees, honestly do not understand how to get done the things you have listed.
I use the
Stealth quality is better than no quality philosophy in that it tends to get better results with managers than a list of things to change.
I predict he will not be able to use your list constructively, even though it may indeed be dead-on accurate.
I instead suggest you develop structured suggestions for each point and present them to him, one or so at a time according to imminent needs or the subject at hand. Each point should include:
1. The need.
2. The practical means to get it done. Step by step if necessary.
3. Why it matters.
4. How you'd be able to tell it's working.
5. How it would improve the company, or him; even improving his quality of life like havoing to spend less of his time reviewing and updating documents. Make it sound appealing.
Please buy and read The Change Agent's Handbook by David Hutton.
I hope this helps!