WordPress as a transparent CMS?

Hi,

Apologies if this post is not in the right section.

I know this is probably a stupid question but is there a way I can find themes for wordpress that just look like normal websites?

Also, is there a tutorial out there which shows how to turn an existing static website into a CMS powered by WordPress?

Lastly, are there limitations on using this for commercial purposes? Specifically, I would be creating websites for people – firstly is it allowed, secondly, must there be a wordpress link on every page?

Thanks

Jody