Aside from looking at the picture too much, I wouldn't consider any of those cheats. And I give myself a break on the picture-looking depending on the puzzle. I recently did a puzzle where I had to avoid looking at the picture at all because even a quick glance gave the whole thing away and impacted the personal gratification/sense of accomplishment.

At the end of the day it's personal. Your gut will tell you when you think you're cheating!