On ipTables, take a look at the saerch section in this forums and search for iptables, there are quite a few threads on this already ;-)
about the 192.168.0.100 and 192.168.0.104... maybe you haven't enabled DHCP? if so, either you enable it, or you just change one of the IPs (in the router or in the host computer).
About auto-starting aMule, use set up /etc/X11/xinit/.xinit (or something like that... the path and filenames depends on the distro). Just add "amule &" at the end of it, right _before_ the window manager.
About a nice documentation on RedHat: The RedHat Bible ;-) quite complete and available on the ed2k network (oh, that's the network aMule uses! what a coincidence ;-P ). But, if you download it, remember to also buy it, so that you support the author, editorial and the copyrights.
Greetings!