License Related Question

According to the terms of the nopCommerce license, one CANNOT remove or hide the "Powered by nopCommerce" statement that appears at the bottom of each page. I understand that a license for $50/- (per site) is required to remove "Powered by nopCommerce". My question is:

1. If we let "Powered by nopCommerce" visible on our website, can we host our website with buying the license?
2. Can we change logo.gif with our organization's logo without buying the license?
3. Will purchasing licence cost only $50/- per site? Double checking license amount.
4. On purchasing licence, will we get "User Guide" for free or do we still need to pay EXTRA ~$20/- for buying documentation?

1. I didn't get you. Please clarify.
2. Sure, you can change it without buying the copyright removal key
3. Correct. It costs fifty US dollars
4. No, you need to pay ~$20 for the user guide