i need some advise in regards to music recordings and copyrights.

Of course you should have a contract defining your respective rights. You're hiring a producer, and normally he'd get points from your artist royalties, if any, and whoever paid for the recordings would own them. Sometimes producers contribute so much to the songs that they want a share of the copyright in the compositions. Since you intend to vary that by paying him for his producing services in advertising, you need to define what kind of advertising and how much, and what will constitute his professional recording of 4 of your songs, and confirm his services are "for hire" and that you (your band partnership's?) owns the end result master recording and musical compositions embodied in those recordings. Your contract needs to provide for what happens if you're dissatisfied with his work and choose not to finish or use his recordings.

I'm guessing that you have no band partnership agreement for your band's MySpace domain name, band name, recordings, songs, and other assets, no publishing companies, no copyrights registered for your songs, recordings or videos, no co-publishing agreements for your song splits, no agreement with your manager or agent, if any, or any other contract or music business arrangement, and no music lawyer. Now's as good a time to start handling your music business affairs with this producer contract. There are a lot of business details in music, so you should hire a lawyer ASAP and get all this taken care of.

Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.

As Pamela said, you really need an independent contractor/producer agreement with a very clear statement that the work the producer does is performed as a work made for hire under copyright law if you choose to hire this guy. You'll also want to make sure your works are registered with the U.S. Copyright Office as soon as they're recorded in the event that he "shares" some of your work/ideas with other musicians in his attempt to bolster his own reputation. While registration isn't necessary for protection the benefits, including statutory damages, are substantial and the cost is minimal.