Regarding sig: Font size 2 is fine, it's the default size so that means you don't need to use size tags. Many people use size 1 for sigs and that works really well too.
What looks best is a matter of taste, but it is always the post and not the signature that is most important. If that's not the case, then why should we care to make posts..? And the content in our posts are never the same in two posts, whereas the sig is the same in all our posts at any give time. So we don't have to read someone's sig every time they post.. So a sig may well be small and subtle and still be good. At least it doesn't need to be huge. Do you get me?
This is well-intended advice and I hope I don't offend you.
The font looks nice now. And they are colored and very easy to read, at least for me. And my eyesight isn't perfect.