This plugin helps to get Google Analytics reports overview to your dashboard using Google Analytics Data API.
Please check if you can select analytics profile in the option page. If you cannot then your email and password may be wrong or you don't have analytics profile attached to that email.
This plugin queries Google Analytics to get the visitors information. This might take sometime. Working on a better way to cache the result for short duration.
Not needed. You have to just upload the files to your plugin directory.
No. This plugin uses some of function of wordpress. WordPress has nothing to with plugin. So de-activating this plugin is 100% safe.