Good idea about the signature etiquette. I should do that too.

About WW, it DOES help with a 50/50 mix, but not as much as with pure water or a lower mix like 80/20 or whatever. The advantage is it provides better heat transfer for added cooling capacity, it was never intended to affect either boiling or freezing points. The idea is that WW helps you ever get near the boiling point in the first place, and if you're near that, you have other issues to deal with!

Not sure about the exhaust smell. I'd expect the leak would need to be pretty large to detect it with your schnozz.