Guitar Hero III Questions

I just picked it up and I was wondering about the following:

1) Can the second player use a PS3 Controller instead of a guitar?
2) Does the Aerosmith version work with the GH3 Controller?
3) Can I play GH1/2 with the GH3 Controller?
4) I heard GH3 Controller will be compat with GH4, is this true?

Thanks

1) Yes.

2) Yes.

3) Kind-of.

4) Why wouldn't it be? It's going to be by the same company.

1) Yes.

2) Yes.

3) Kind-of.

4) Why wouldn't it be? It's going to be by the same company.

djHaQ

What do you mean by kind of?

Thanks for the help so far.