Read this quick launch and indexing guide. It explains many details regarding submitting sitemaps to Google, Yahoo, Live/MSN, and even Ask.com. If you already have a Google sitexmap.xml file, just point to it with your robots.txt file. All the major search engines will find it. There is no need for a urllist.txt file if you already have a sitemap.
No..they use different sitemaps...For google and MSN, XML sitemaps are best and for yahoo urllist.txt is good...
Yahoo can read and count the links in the sitemap.xml file. It is now regarded as a standard web format for the websites sitemap files.