BrettJ, for the first I don't think many webmasters think of that, especially that many complain about their income - i.e. low ratios, missing signups, etc.
For the second: I haven't seen your site or banners, but supposing you have on your banners
www.dormangels.com or
http://www.dormangels.com , do you thinks surfers see it as an established brand? I mean people complain about sites being overexposed, so those who do know the brand, might have already joined or saw it in the past and don't like it, while new surfers who should be the target (more likely to join), don't know about that brand.
I see what you mean, but I would prefer banners without the url. Maybe sponsors should create both type of banners, with and without the url.