That signature problem isn't that big of a deal. Once it gives you an error scroll down to the "country/language" box and check the one that applies to you. After that, go down and upload your signature again. It should work like a charm.
Seems to work in FireFox now ... and on Safari (not that I've spotted many Mac types out there) .... I've also had a bash with Camino and Opera (PC and Mac) and they all seem to work .... doesn't work in lynx though :-(
I am still unable to get it to work with Firefox, mine is still just a plain white box with text in it. I will check on my other computer right now because that is where I am headed. I will let you know if it works then.