Melanie,
It appears the name Zimmerman (which also appears in my family tree in Canton Bern, by the way) is one researched by genealogist Julius Billeter, who researched hundreds to thousands of surnames, using the original Parish Registers, and created pedigrees of thousands of families prior to his death in the 1950s. If you live near a LDS (Church of the Latter-Day Saints) Family History Library, you can order the film containing Billeter's notes for the Zimmerman family. Although his notes and writing style take some getting used to, you can find a lot of information in a very short time using his notes. I was able to get two of my Swiss families (Käser and Hochuli) from the mid-1800s back to the 1500s in a matter of hours. The film which contains the Zimmerman info is #193488. When you get this film, you will need to go to the Zimmerman family, and find your ancestor in the notes for Wattenwil parish. You may be able to find some of your other families also - the name Rufener also appears, in film #193482.
You can find the FHC nearest you by visiting the LDS site at
http://www.familysearch.org/Eng/Library/FHLC/frameset_fhlc.a.... Click on the Film/Fiche search button, enter one of these film numbers, and it will bring up a (partial) listing of the names Billeter worked on.
Eventually, you will probably want to verify Billeter's findings against the original Swiss Kirchenbucher, but his work will be a great aid to you in the meantime. I just checked at the LDS site - while it appears that the Wattenwil records have been filmed by the LDS, baptisms do not begin until 1660 so this film will not help you verify any individuals born before then. Unless another filiming of the earlier records has been made elsewhere, this research might have to be undertaken in Bern itself.
If you have any more questions about how to go about ordering the films, or how to read his notes when the film comes in (he uses a lot of abbreviations instead of full names, for example), feel free to email me privately.
Good luck!
Toni Skidmore
Chicago