bread crumb definition, see
Baking Glossary | The Fresh Loaf
I can't imagine 100% of all bakers world wide will agree with any one specific definition, but it's a start.
proofing time will indeed affect the end result - both "too much" and "too little" are problematic.
a time honored 'test' is the 'finger poke' - described by many other words/phrases as well.
again - _depending_ on the intended loaf type/technique ... you poke the proofing bread, the indent should spring back slightly, but not completely. if the 'poke hole' springs back and essentially disappears, it's not finished. if the 'poke hole' does not spring back at all, it's over-proofed.
and after the proofing questions, there's the "oven spring" issue.
I bake a lot of bread(s) and I'm constantly trying new recipes. here's the deal: it's rare when all the stars align and it all works "perfect" the first time. I'd say 80% of my attempts do not "look like the picture" first time. if it has good taste or some other characteristic I like, I keep at it. you'll frequently see recipe directions that are a bit fuzzy about qtys. well, after you make a recipe a couple times you figure out what more/less you need to make it look like the picture (g).