That's unfortunate about your garlic. I have actually had a few people tell me this year their Garlic did not do well either. I will keep the trimming in mind in the future, I actually did not know that. Probably what happened to my friend as well.
I fell you on the weeding, what I did last year was throw some ply wood in a few spots. It seemed to work well, the only issue I had was it seemed like the gophers really liked the cover and made a home under neath!
I have some landscape fabric that I am probably going to put down next year if I do anything. Hopefully that will help. There is a point with garlic where the scapes start forming and you trim those off, but having never seen them before, I thought they were ready and I was wrong. I ended up cutting off some of the stem.