Google Webmaster Tools Site Errors

I am getting a couple errors in my google webmaster tools account about my sitemap, robots.txt and google not being able to index my site lately. For some reason it is pulling my sitemap.xml.gz instead of my sitemap.xml and I have infinite seo installed. Has anyone else had this issue? I went into my website and unchecked the gz option and then resubmitted my sitemap to google. Do you know about how long it will take before I get an update in my webmaster tools?

Also, I guess I have a basic Google Webmaster Tools question. My domain is http://MyDomain.com - what is the domain I enter when I add my site to webmaster tools? Do I just add a new site as: http://MyDomain.com? Or do I enter MyDomain.com, http://www.MyDomain.com or all of these. I just want to make sure I have it set up correctly. Thanks.