Hi can anyone pls help me to answer this:

1)When usually the background check will be done? Before the company give the offer letter or after?
2)What if I lie during my application e.g. I put my current salary high
3)Can future employer check about my current salary/epf record. Or when I joined them, can they track my past epf record?
4)Can my HR disclose my payslip if future employer contact my current employer?

So how to answer let say the company insist to know my salary? I know the salary should be P&C. I think all company's policy is not to disclose your salary.