On the customization front, this useful tool allows you to insert code into your iWeb sites by wrapping it in a specific tag, as well as customizing the site-wide header and footer with dedicated chunks of code (pictured).
As far as getting your recently-created iWeb site to where it's going, iWebFlinger's FTP features are pretty handy. Your password is stored in the system-wide Keychain, and you can even upload a favicon (the neat little custom icons that appear alongside a site's URL in the address bar). iWebFlinger also has the option to be smart about exactly which files it needs to upload and replace, which can save a lot of time when you make additions or changes to your site.
iWebFlinger is donationware from Chris J. Shull, and it's available at his site.