After uploading my sitemap.xml file to Google Webmaster Tools I received the following error message and no additional error details were included:
Error: The last attempt at downloading the Sitemap failed. The details below are representative of the last successful download.
I searched around a bit and found a forum post where someone said they get this error ’sometimes’, but after switching to use a gzip formatted sitemap.xml file the error went away
on ubuntu
gzip ./sitemap.xml
compresses the file to ./sitemap.xml.gz and deletes the sitemap.xml file by default
after uploading Google was able to process without issue
But it can't hurt to include one and submit it to Google, Yahoo, Bing and Ask; it definitely won't hurt your page ranking.
I do not think so.. Moreover this blog mentioned below will lay more light to what I want to say..
http://www.redalkemi.com/blog/sitemapxml-the-most-overrated-search-engine-indexing-factor/