You are delving into a very complicated and intense subject here and the question cannot be answered with a simple yes or no.
If you are planning to view the finished video on a pc then you could really do it at whatever FPS suits. However if you are planning on putting it on DVD that is a different story as the video and audio have to be a specific type and standard (ie. you cannot use any audio other than MP2 for a NTSC 29.970fps dvd)and the video standard has to be mpeg 2 otherwise a standalone DVD player will not play it.
Most new European players will play NTSC or Pal, but from my understanding it is harder to find a player in the U.S that will play both colour systems.
15fps is not a good idea for finished playback speed in general because of the motion blurr problems and it will be difficult to avoid it being jerky...ect.
Hope this help...goodluck.