I have been down the same path that you are going and asked the same questions. What I found was this: there are two major ways to sculpt in wax or how wax is used in toy production. The first is to sculpt the model intirlly out of wax using a wax pen, carving and etching tools. The other is to sculpt the model in clay and then make a mold and then pour wax and make a wax cast. From there you then sculpt/carve the finner details. I found this site very useful in the proccess of the wax casting:http://www.designinteract.com/features_d/asylum/index.html
I like the ability to shape the clay with my hands and work in as much detail as I can before my finger prints start to destroy the details. I defently prefer to do my final detail work now in wax.
The other thing you asked about is the aquireing of "Hasbro" grade wax. Well Rick as well as Glassman and myself, get our wax from Bantha 5. He makes his own wax which is as close you are going to get to "Hasbro" grade wax. You see, Hasbro wax is a guarded special recipe from what I have been told. The next best thing is to try other type of waxes. I only found this brand, Azbo wax:http://www.sculpt.com/catalog_98/Wax/Azbro.htm
I have heard mix reviews on this. I have not bought any my self, only used Bantha 5 stuff so far.
The last thing you asked about "is it soft or what?" I will tell you this, it is not the same as candle wax. it is much harder than that. The two samples that Bantha 5 has sent so far are actually two types of wax hardness. The first sample I got was hard but had a silky feel to it. I only had to apply the slightest amount of preasure to the model with my tool to make changes. And it melted real easilly over the candle. The last batch that Bantha 5 sent me was a harder type. When I casted the model using this wax it felt like plastic. Really strong stuff especially for little old butterfingers me who drops things from time to time. The wax when melted, was a lot thicker than the first which could cause problems when pouring into a mold. To counter this would be to pre heat the silicon mold so that the wax would not have a chance to cool down before your done pouring the wax.
Glassman and UK Rick have been doing this much longer than I have and I hope they will have time to chime in as well. Bantha 5 hangs out mostly at Rebelscum than in here so if you want to pm him you will have to do it there (I think
I hope this helps some.