will there be dawnguard official patches or just the unofficial patch only?

Maybe both. Official Patches are made by Bethesda and Unofficial Patches are made by the community. One does not preclude, or include, the other.

I wouldn't hold my breath for a patch any time soon. I doubt they would risk more grief from the PS3 users by releasing patches before the PS3 DG problems are fixed. Saying that, then they risk everyone else moaning at the lack of patches. Beth has dug themselves a pretty deep whole over all this and are struggling to get out intact. I hope they can though for their sake but for the love of the 9, they need to step up on their quality assurance. Monkeys could do a better job.

I think that Bethesda must finish Dawnguard on the Ps3 first before they decide to put in patch updates to fix certain issues because in SO many news articles the concern is not the issues at the moment but the fact that added issues from Hearthfire or old issues on the Ps3 still exist makes the DLC more and more harder to release