> 3. How do I keep my DHCP IP (my ISP does not offer static IP for
> residential customers) fairly constant, over say a period of a day or
two?
> Do I need to setup a cron job to send traiffic out (like a ping) every
few
> minutes to keep the connection active? If so, how do I setup a cron job
> (I've never actually had to do that before)?
Not really necessary provided your firewall gets the external IP your
looking for. If it does, you can use a dynamic dns updater like
ddclient, ez-ipupdate, or ipcheck to update your IP with an external DNS
server.
> 4. How insecure is it really to enable X forwarding over SSH? I have
> heard that it is not advisable becuase of security, but how bad is it?
AFAIK, as secure as your SSH tunnel. It tends to be slow, forwarding
VNC over an SSH tunnel is normally faster.