You should include both the citation and a footnote (Purdue). In Chicago style formatting (17th ed.):
The author’s name is inverted in the bibliography, placing the last name first and separating the last name and first name with a comma.
Titles of books and journals are italicized. Titles of articles, chapters, poems, etc. are placed ...
You are correct in noting that it is common to add "Emphasis mine", or similar, if you add emphasis to a section of a quotation.
It is equally common to add "Emphasis original", or similar, if you retain the original italics or bold font.
That way it is clear to the reader that it is not you that is adding the emphasis.
If you wish to ...