The only time i would bother with a sitemap, is to make a html page one, not really a site map as such, just a list of links with surrounding text to help with internal links. 
And i have never tried adwords on a brand new site, but as said, if you have a blog that gets indexed within a few minutes of pinging you just have to link to your new site and google will index it quite quick.
If you just ping a new site it will generally take longer to index than a link to it. 
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