Sounds like you bumped into a lot of crazy people that day!
First I'll say that you did the right thing by actually staying with your dog. If I had a dollar for everytime I saw a dog tired up outside for half an hour in the middle of an Adelaide summer...(half of them were quite anti social and aggressive too)
I second getting her a muzzle when she gets older, or even just putting one of those halti things on (some people can't tell the difference anyway and will stay away from her).
Annoys me to no end when people offer dogs food...they don't know what allergies the dog may or may not have, not to mention how many dog owners don't know what foods you shouldn't feed dogs. Then they don't think about food aggression. Stupid people.
I think you handled it as well as anyone could. I'd especially have told the annoying woman where to go :P so inconsiderate.
Hope the crazies leave you alone next time!