if you ever visit
www.madsci.org, and search their archives, you'll find a large amount of discussion to your questions about the whole massless photon debate (of course, there are MANY other topics). There was a recent discussion by a post-doc named Phil Marsden where he imparts his views on photon interactions. The most interesting thing I found was this new field of study on QUANTUM HOLOGRAPHY... here are some interesting links
http://unisci.com/stories/20014/ 1126013.htm
http://www.aip.org/enews/physnews/2001/split/566-1.html
I got these sites from Marsden's article.... enjoy them! They are interesting!
