How can I find quotations from the era of William Shakespeare that relate to the political as well as to the themes of money and power in Macbeth?
I am looking for 2 quotes from the text and one quote from the time period when the play was written (which supports the 2 quotes from the text).
There are really 2 separate questions in your notes. Since you'll be able to find the quotations from Macbeth as you read through the play, I'll address the question of finding other sources.
There are two ways that you can approach researching this question, one by starting with secondary and one by starting with primary sources.
For primary sources, the best place to look is in the "mirror for princes" tradition, books intended as advice for rulers. Isocrates' Busiris, which was popular (in translation) in the period serves as a model for many of the Renaissance compositions in the genre, as does Machiavelli's "The Prince". Perhaps your most important source would be Sir Thomas Elyot's "The Boke named The Governour".
Many secondary sources will include references to primary materials. Tillyard's Elizabethan World Picture is a a classic well worth reading -- it's short and readable and quite astute. Another option is to go into the catalogue of your university library and search the MLA bibliography (you'll find it among e-resources) to find secondary sources on power and money in Macbeth.