Only in the presence of water :-) If you want that route, pick one of the lower elements from that column...potassium or cesium (the latter being hard to get)

I think you're talking about white phosphorous. Sodium phosphate (mono-, di-, and tri-baisc)is a boring old salt, useful as a buffer at neutral pH. http://en.wikipedia.org/wiki/White_phosphorus http://en.wikipedia.org/wiki/Sodium_phosphates

Thermite != KABOOM. Honestly...you call yourself a geek and you've never made thermite? A little iron oxide powder (rust), a little aluminum powder, and some activation energy.