1. Peronsal prefrence I say 4

2. The only question I cannot awnser

3. If you mean free software Kitra if your pc can handel it or gimp if you want something that takes up less power... Also MSPAINT but don't.

4. Depends on what your useing I would reccomend looking up a guide on whatever engine your useing I think unity has a ton so if your using unity there you go.

Firealpaca is a good free software for making art