How you configure apache (or tomcat) depends on your linux distribution, I nomally use apachecfg to do it.
re 2) Default apache config installs a "web folder" (usually /var/www) under which you need all the files, or a link to them.
Direcories, and other things are specified in the configuration files (/etc/apache/*.conf) and should be changed there (this might break your linux distribution's autoconfiguration/installation)
re 3) I dont know what you mean by "ensim control panel", and there's no "dos prompt" in linux, only a shell (same thing with a different name).
I think there's a cgi-script somewhere that'll tell you the current configuration of apache, read the excellent docu that comes with apache.
Same goes for tomcat/cocoon