Hi harosha,
Congrats on your purchase. I started with a PSR640 (almost bought an XP60 and then upgraded to a 9000PRO and have never looked back - a great instrument. I agree with everything that ChicoB has said. You will find many, many styles in the Yamaha PSR Styles group. Are your songs in MID format? If so then with a bit of reverse engineering using either the 9000PRO or software such as Cakewalk or XG Works (my preference) then it is possible to build your styles from MID Songs. A style file once the formating is stripped away is a lot less complicated than a MID Song file (my opinion only). Although, I guess if they were "my" songs which I had written, then I would probably opt for recreating them using the style tools at my disposal (9000PRO and software).
You might try putting out a message on the Yamaha PSR Styles group for a collective opinion - there are many eager and capable helpers in the group and you will find youself not lacking in suggestions to solve your problem.
I hope this is of help to you.
Jon.