Use the Catch Everest Free theme for a fishing site

Hi, I tried to search but not find any answers at my questions. I want to use Catch Everest Free to a site there we will be selling tickets so people could fish in the lakes we have. I´m not really sure what you call it in English but maybe just a Fishing Association. Is it ok to use this free theme for this? I just want to be ensure so we don´t do anything wrong. My other question (if the answer at the first question is no, you not need to answer this) is if I now want too make changes in the CSS file and other things. Should I change the text in the bottom of the page "Theme: Catch Everest" to anything else? I just think if a change the style pretty much I maybe should rename it too example to "Catch Everest Child Theme". I hope you understand my questions. / Tiger