Here is the link to the familiarization manual (28mb pdf):
http://ntrs.nasa.gov/search.jsp?R=8...tx=mode+matchall&Ns=PublicationYear%7c0&N=302
And this link is for the "mercury" general search. The filters are set for "technical reports" only but you can broaden the search to include photos, video, and other types of media. Not all of it is available on line (although much of it is) but you can order copies of the rest for a price. There is so much material available on line that I have spent about 6 weeks of spare time effort just looking through the technical reports alone! Incredible, and it is for my favorite price: free (!):
http://ntrs.nasa.gov/search.jsp?Ns=PublicationYear|0&N=302&Ntk=all&Ntx=mode%20matchall&Ntt=mercury
Note: If you spend a lot of time searching this site, don't forget to book mark your last page. I got over 5,000 hits for just "technical reports" when I used the search term "Apollo", which equates to over 500 pages of listings, and a book mark really helps instead of having to page through all those listings looking for where you left off last time.