A great place to start is the PrPro-Wiki, which has tutorials for PrPro. I'd recommend not just looking at those particularly for CS3, as one can easily interpret from earlier versions, and also from tutorials for CS4.
Another site for tutorials, is Curt Wrigley's. Many are for earlier versions of Pr/PrPro, but they are easy to interpolate. I even link to these for users on PrElements.
As for your particular questions, most can be done right in PrPro. You will want to read up on the Titler, for the text. It is a great application, and is right in PrPro.
The Audio clean up can be a bit more involved. I use Adobe Audition for this, but that is a separate program, with much more power.
Here is a look at Titler, so that you can see some of the Tools available there:
Titler will allow you to create all sorts of Titles, and they can be used in many ways, in PrPro. The program comes with several Title Templates, that can be used, and modified. From the main Toolbar, choose Title>Based on Template and then look at the Templates in the Library.
Good luck, and after reading up on Titler, if you get stuck, just tell us what you are doing, and what is not working for you. There are some little "tricks" in Titler, but without a background, they would be worthless now.
Also, there are several Titler tutorials on Curt's site, linked above, and some on the PrPro-Wiki too.
Last, Curt Wrigley has published a great book, Adobe Classroom in a Book Adobe Premiere Pro CS3, Adobe Press. He also did the CS4 version too. He covers almost every general topic in PrPro, and does it very well. I highly recommend that book.