Great little essay about quotation marks
Regarding "." and “.”
Well, perhaps rather obviously, it’s a compromise created by the lack of space on original typewriter keyboards (more specifically, lack of space inside the typewriter for the extra workings for more keys). There wasn’t room to have an extra dedicated key for left or right quote/apostrophe marks, so a single key was used for a new “ambidextrous” set of quotes and apostrophes. As typewriters were a way of getting words hammered onto a page; faster than a scribe, easier to read than most people’s handwriting and always consistent, no matter who was doing the typing, this compromise was acceptable. If you wanted to publish your words, you would send it to a printer where typesetters would take your words and use their typographic skills to make them readable and (hopefully) beautiful.