These texts are transcribed (with updated spelling and paragraphing) from the History of the Life of Mary Queen of Scots, printed in 1681, microfilmed in 1976 and stored at Ann Arbor, MI. As far as we can tell, it is otherwise unpublished. The text appears to be in part drawn from Camden's Annals and the relevant calendar of state papers, which provides a more complete transcript of the trial and narrative of the execution. The History also includes a rather long introduction; I have chosen to give you just the letters and other documents, and spared you the polemic. (It also includes the trials of the Duke of Norfolk and Philip, Earl of Arundel, which I may get to at another time.)
Why 1681? The publication a hundred years after the events was evidently prompted by the political issues of the late 17th century, when serious pressure was being brought on King Charles II to prohibit his brother, the crypto-Catholic Duke of York (eventually James II), from inheriting the throne. In this interest, mining relatively recent history for examples of Catholic perfidy produced numerous popular—and best selling—books and pamphlets. The History is one of those books.
Given these circumstances, it should come as no surprise to the reader that the tone of these documents and reports is neither romantic, as in the Victorian mode, nor what we might call balanced reporting. The documents are nevertheless fascinating as a look at both familiar events and the world that reported them.
For a complete timeline of Mary's life and death, you may want to look at http://www.marie-stuart.co.uk
For a more complete collection of the Scottish queen’s letters, you may be interested in Agnes Strickland's 1842 work, Letters of Mary, Queen of Scots, and documents connected with her personal history, available at Google Books
For the modern views on Mary, see (among others):
16 March 2009 pkm