Yes, just enter it as you want it to appear: Updike, John, and Henry David Thoreau
No, the plugin will handle it for you.
No, the plugin will automatically italicize the titles of books, magazines, and academic journals.
The "Additional information" will be appended to the end of the citation paragraph. A note gets added below it, in a separate paragraph. See the screenshots for an example.
"End punctuation" is what comes at the end of each part of the citation. For example, a period after the author(s), another period after the title, etc. "Internal punctuation" refers to punctuation within each part of the citation, for example, the comma in the author's name: "Lastname, Firstname".
No, but they will be added in a future update. They can still be accessed by adding the appropriate shortcode manually.
No. All your data is entered into your post as a shortcode, so you can edit your data in the shortcode.