In regards to the first two, I think you need to move a little bit lower to really be at her level. In fact, I'd almost move below her eye level. Alternatively you could flip the bill and shoot entirely above her, pointing down, and letting the shadow do it's work in the water. Just some things to consider. I don't usually think about this stuff at the time much.
If you don't have the light, the background is too busy, and can't really get the shot you want, then I'd just say forget it.
I agree with you entirely when I am shooting commercial work but when things like this present themselves I rather just shoot and have the image. A mentality that I cannot seem to do with my MF gear only 35.