I, like you, am searching for a viable framework as well. Most if not all frameworks are OOP (object oriented programming). ZEND is probably the best since its actually supported by the creators of PHP, but there are other frameworks like Codeignitor that promise speed and ease of use. CakePHP also seems to be pretty popular.
I'm sure you can find benefit in using these frameworks, but expect to spend a weekend or two just learning them. I spent a long time trying to learn Codeignitor, and covered a lot of the basics, but still have a ways to go.
All in all, yes, you can get extra premade functions built into a framework, but that means you have to not only learn how to install and use the framework, but how to modify and add to the functions if they don't do exactly what you want them to. Ask yourself if it's easier to just make the functions yourself, or if its worth learning an entire framework just to use theirs.