You can give as many payslips as u can manage, they are basically just supporting documents to your CV and a proof that you were working at the company as mentioned in your CV.
One applies for the state sponsorship when you want to speed up your application processing or when one is short of points. As you might be aware, since the changes in processing priority they give preference to applications with state sponsorship, those in CSL and MODL. No one can really comment on how long an application that doesnt fall in any of these categories will take. There are also people who do not have 120 points to apply for the visa, so they take state sponsorship to gain points.
I dont know if IELTS band score 7 and above is the criteria for CSL but I am sure it is the criteria for state sponsorship.
let someone comment on this one