so I finally got the opportunity to have a look into Thinking Particles working together with Xpresso.
the video above shows an emitter tangentially aligned to a spline. the particles bounce (even with some friction) when hitting the water – which actually is just a plane bumped with an animated noise shader. and we have this newton-thing … aaahhhh yeah: gravity. I also like all these particle-settings “over lifetime” and i guess i found myself a module of Maxon´s Cinema4D that i´ll upgrade to in the near future.
the depth of field was done in after effects using a rendered z-depth image.
btw: does anyone know why the TP-particles don´t show up in the z-depth-channel ?

//edit: download quicktime HD 1080p h.264