As author of the notes for the first three entries for the Sonatas and Partitas, I can also recommend Jaap Schröder's book
Bach's Solo Violin Works: A Performer's Guide (Yale U.P. 2007) as a must-read for those tackling these pieces who want to get a historical-performance perspective on interpretation. Unfortunately, it is rather expensive for a small and relatively short volume.
There are two other books that might be of interest:
Bach's Works for Solo Violin: Style, Structure, Performance by Joel Lester, which concentrates more on style, structure and analysis and less on actual aspects of performance than the Schröder book. There is also the brand new
Unaccompanied Bach: Performing the Solo Works by David Ledbetter that I have seen in a bookstore but have not yet had a chance to page through.
And if you really want to spice up your life, try a good Baroque bow (e.g. the reasonably priced items at
http://www.vanedwards.co.uk/bow.htm, and not the items sold on eBay or by Shar music). Even used with a modern violin, a few minutes with a good Baroque bow will be a revelation. The articulation effects are completely different from a modern Tourte bow, and phrasing works differently (because of the more pronounced changes in loudness at different parts of the stroke). The next step in authenticity would be to try pure-gut strings, such Pirastro Chorda, with possibly a metal-wound G. Most "authentic" instruments you hear on recordings are this combination of features (period bow + gut strings), with few players going the extra mile to have a violinistic liposuction (shortening the bass bar) or other corrective surgery (changing the alignment of the neck).
As for critical editions, I'd recommend the Barenreiter score, which is still under copyright. But you're going to have to figure out your own fingering since this edition is just the notes (essentially a engraved version of the composer's manuscript available here at IMSLP for free).
--Sixtus