Yes, the "New Identity" option clears just about everything. It even seems to clear the clipboard.
I'm not completely sure I understand. But I think the answer is no. In general terms, Tor hides who you are, not what you do. In other words if you go a website, read page A and page B. The website will know that somebody
visited those two pages and at what time each page was viewed. They just won't know it was you who did it. Or if if you used the "New Identity" command before viewing page B, they won't even know the same person viewed both pages.