My first point is clearly a 'bug' though: writing "2. something" shouldn't create output that looks like "1. something".

Or, at least, it is a feature which someone could legitimately not desire. The numbered list feature is just a way to specify html - so like in html the formatting is up to CSS. If you don't want a vanilla html numbered list generated then you just have to do the numbering manually and once again escape the character for the unwanted syntax. In this case that means the period.

2. One
1. Two

Yes, this is somewhat annoying to do. It is also annoying that you don't have control of the CSS used from inside the markdown. Which gets frustrating for nested lists when the default formatting sucks. Come to think of it that's another feature request. Change one line in the CSS to improve nested lists.