Google Adsense 3 short questions

I have a website and I am now thinking about adsense to earn some money.

I have some questions though:

1- Is there any way to make Adsense look better? I hate the white background and the bl开发者_运维技巧uish border around it, is it possible to style it?

2- Is there any formula for how much one makes? The website is a classifieds website, which means all kinds of people visits. But is there any formula like x Visitors = x Money?

3- Will it slow down my website performance?

Thanks

1) You can customize the look

2) I find around 0.5% click rate

3) Performance impact will be negligible