i planned on giving a brief introduction into the invention and mechanics, the politics behind germany being the only ones who had this during WWI

Germany was not the only power that had this weapon. The Russian Empire used the PM1910 Maxim extensively in both World Wars and the British used some Maxims early in the war alongside their Vickers-Maxim Gun, itself is no more than an improved and lightened Maxim Gun. This and most other powers had their own Machine Guns of equal tactical value, Italy had the Fiat, Austria the Swartzlose and France the Hotchkiss.

looking for both primary and secondary sources concerning the Maxim machine gun.

Well I don't have a lot of WW1 resources but I do think I found something you might be interested in. A book published in 1917 by a British Major Fredrick Longstaff (bit of information on him here) who was sent home in 1915 and a Captain a Hilliard Atteridge. It is called "The book of the machine gun" and it has been made available by the University of Toronto (Here). A look at the authors preface has it well sourced and the table of contents says it has most of the information you are looking for but it is an old publication. Perhaps it would be a good read along with a more modern book.