1. Installing source package with YUM

  To install source package with YUM you have to install yum-utils
   yum install yum-utils
  then, just use yumdownloader:
   yumdownloader --source packagename
 example: use '$ sudo yum install net-tools' to download
  net-tools-2.0-0.2.20121106git.fc18.src.rpm
2. Uncompressing / unpacking of source
  Source RPM archives (.src.rpm)
   SRPM archives usually don't need to be unpacked before using
   them (see Section 6>). In the rare case that you really want
   to unpack an RPM (regardless whether it is a source or binary
   RPM), you could do it as follows (note that you need the
   utilities rpm2cpio and cpio):
    rpm2cpio foo.rpm | cpio -idmv --no-absolute-filenames
  In the case of a source RPM, the content will likely turn out
  to be two files — a .spec file and a tarball (see above).
    Tip TIP
  If you simply want to list the contents of an RPM package file, you can do that with
    rpm --query --list -p foo.rpm