1. Why something is missing

There are different reasons why something may be missing from your system.

• You did not install all the packages. Most Linux distributions let you add the packages on the fly. On Debian systems, use the dselect. On Red Hat systems, use RPM or Gnome-RPM. On Slackware systems, use pkgtool.
• Your distribution has non-standard components. Most distributions (for some time now) agree on the Filesystem Hierarchy Standard, a document which describes where things should go. However, sometimes things aren't exactly right. Some Red Hat 3.0.3 CD-ROMs contained /usr/sbin/portmap and some contained /usr/sbin/rpc.portmap. Most distributions contained the latter. Anyway, if you will have non-standard components, you'll need to investigate and fix the path used by Linuxconf.
• You did not intend to run this package anyway, so you did not install it.