Hi blue,
Thanks so much for creating a separate thread.
#1 This has already been reported, and we’re working on it: WIP: External files: repeated image default styles
#2 There is no differentiation or separate text/image logo classes, so the default styles stay since text is the default.
#3 This is to be able to address them specifically if you have multiple navs, e.g. in the header and footer.
#3b (last sentence) If you are referring to the article, aside, figcation, … or *, :after, … rules: they come from the browser reset css and still make sense.
Overall, none of this is a bug (as you say yourself) but minimal improvements, so I’ll move this report. However, I’m pretty sure these few lines will certainly not influence your website’s performance.