Okay, a couple things.
First - basic knowledge of Networking would probably really help you here.
ANY IP addresses in the 192.168 subnet are NON ROUTABLE, this means you cannot SEE them on the internet.
Same for 10.0.x.x, 172.16.x.x.
So, you will ALWAYS need to figure out what your WAN IP is (the IP address of your router in the house).
I've got another solution - why not let D.Net host the FTP site and website?
We're already hosting several other sites, and considering we're in a dedicated facility with a enviromentally controlled NOC....
Best part?
IT'S FREE.
So, someone want to get with me? I can set it up where you can have an admin FTP account, and then a Logon account (or accounts) that have access to the FTP site itself.
ONE word of caution: Do NOT allow anonymous write access - meaning DO NOT allow people to put stuff on your FTP site without having to logon.
I PROMISE you within a couple months you'll have pr0n, ripped movies, etc. etc. and considering what I've read so far I doubt you'll be able to remove the directorys from the FTP structure itself once they've found your site.
ALWAYS use a password protected account for write access to the site.