Unfortunately the Web is not a perfect place and a customer's Website might use abominations like popups and mixed SSL.

You can work around these bad practices by using config/includes.chroot/etc/iceweasel/profile/hostperm.1:

# Permission File
# always allow popups and session cookies from example.com
host    cookie  1       example.com
host    popup   1       example.com
host    cookie  1       www.example.com
host    popup   1       www.example.com

To deal with SSL warnings in Firefox, I've employed:

hendry@h2 webconverger$ grep security config/includes.chroot/etc/iceweasel/pref/iceweasel.js
pref("security.warn_entering_secure", false);
pref("security.warn_leaving_secure", false);
pref("security.warn_submit_insecure", false);
pref("security.warn_viewing_mixed", false);