iFrame ethics and laws

I’m a very rookie developer and would like to know the ethics and laws around using .

The way I understand it is that it is a window to the site, and any views or clicks on ads/links would still count to the original site – is this correct? Is there any harm to the original site when using an iframe?

Also, what would the effect be on their and revenue if you forced the iframe to load their mobile site?

Thanks for your time!