Once you have your pictures every n seconds, you can use VirtualDub (Windows) or AviDemux (Linux & Windows), you open the pictures (just open the first one, all the sequence will be loaded), you set the frame rate (eg 15fps), set the video encoding (eg xvid or h264), and you save...
For how long between shots, it completely depends on what you want to do, it can go from one second to one day (hum, maybe don't use a script for one day ;-) ). Only the result you want can drive you (if you're not sure you can take more pictures, and keep one every two, or one every three, ...)
