Guidance on SAP PS

Can anybody answer the following questions regarding a career in SAP PS?

(1) Is SAP PS - Project Structure or Project System?

(2) How good is SAP PS currently in the market? I mean, can anybody expect a decent pay and growth in this module?

(3) Who is actually suitable for this module? I mean, a project management experience of more than 3 years and an interest to do SAP PS are sufficient?

(4) Is there any specific approach for this module or is it just like any functional module?

Any advise is highly appreciated