Hi AF330,
1. The APU bleed air goes only to the starter motor. The starter motor uses this air to turn a shaft that is connected to the compressor of the main engine. The fan is turned by the rotation speed of the Low Pressure Turbine at the rear of the engine.
2. The fan takes air in but keep in mind, most of that fan air goes around the engine, not through it.
3. Your question isn't clear enough to answer.
4. To answer this question I would suggest you go to this Rolls Royce learning site and go through each of the 4 presentation stages. It will help you to understand the different sections of a turbo-fan jet engine and how they relate to one another:
Journey through a jet engine
I hope you will enjoy this!