Recommended textbooks:

Path integrals and all that ...

Laurie Brown (editor) and Richard P Feynman, Feynman's Thesis:  A New Approach To Quantum Theory, World Scientific, 2005.  (Available as an electronic resource from the UM library.  So, if you are at UM, you can read it on your computer without any cost.)

Richard P Feynman and Albert R Hibbs,  Quantum Mechanics and Path Integrals, McGraw-Hill, 1965.  (A classic, but unfortunately now a collector's item and quite expensive to buy.  See here.)

Hagen Kleinert, Path Integrals in Quantum Mechanics, Statistics, Polymer Physics, and Financial Markets, 5th Edition, World Scientific, 2009.  (The 4th edition, 2006, is available on Amazon for less than $40.  The 3rd edition, 2004, is available as an electronic resource from the UM library.)

Christian Grosche and Frank Steiner, Handbook of Feynman Path Integrals, Springer, 1998.  (Unfortunately, again, this is not cheap.  Rather, > $250.)

QM in phase space ...

Cosmas K Zachos, David B Fairlie, and Thomas L Curtright, Quantum Mechanics in Phase Space:  An Overview with Selected Papers, World Scientific, 2005.  (Needless to say, a personal favorite.  One of several bridges between the formalism of path integrals and the physics of quantum optics.)

Quantum optics ...

John R Klauder and E C G Sudarshan, Fundamentals of Quantum Optics, Dover, 2006.  (< $20!  An oldie-but-a-goodie, reprinted from the original 1968 edition.)

Wolfgang P Schleich, Quantum Optics in Phase Space, Wiley, 2001.  (A bit more expensive than the previous.  That is to say,  > $100.)