1. Yes
2. Yes. No other details are required.
3. Yes.
4. They should have sent back your 'invalid' PO. You can ask for it. In whose favour did you draw the PO first? Refer to DOPT circular dated 1.4.2008 available in the site
Right to Information Act (India). If you had drawn it in favour of the Accounts Officer they should not insist you to draw it in some other name.
5. No need for appeal at this stage.
6. Send it to the current name of the CPIO. They keep changing.