There are two issues at work here:
#1) Jacob is correct, you cannot have something on the stack resolve without both players passing priority
#2) It is possible to respond to your own items on the stack before your opponent would get priority. So you can play Cavern Harpy and respond to its ability by playing another spell, and your opponent gets no chance to respond between the ability going on the stack and you playing the next ability or spell. However, your opponent will still get a chance to respond when you are done with effects (and after each thing on the stack resolves). So after you play all those effects, your opponent still gets a chance to respond to each creature's comes into play ability (or the creatures themselves once you pass priority).
Edit: I walk through the timings of some of this in more detail here:
http://www.themanadrain.com/index.php?topic=33628.0