have a site that i have had for over 8 years now and have not paid to much attention to it lately since i have been working on other projects. I decided to check today how some random ones were doing and discovered that i am getting a fair amount of traffic to a site a month and i do not have any ads running on the pages that are creating the traffic. Figured i would fix this and ad some ads and start updating the site along with adding a new sitemap to the site since i have over 200 errors of not found pages on there from the last time i updated. Main question is will doing all this stuff hurt my keyword ranking on search engines? i am on the first page for alot of main keywords and do not want to have it screwed up by making these changes. Any Advice?