The 'starter pack' includes both the project board and a battery box. The software needed is free, so all extra you need to get started, is a computer and batteries. Furthermore, free training resources and tutorials are provided in the PICAXE manual (Part 1 - Getting Started).
Adding the full range will enable it to simultaniously control 4 servos and 2 motors, and communicate via the accompanying Infra-Red remote, while still having 8 digital programmable in- or outputs and 4 analogue inputs at disposal.
The project board can be used with any software application that supports the PICAXE hardware, including the free PICAXE Programming Editor and/or Logicator for PIC Micros software.