I’m sure it does. It could be positive, negative or even no difference. It really depends on a whole host of factors which will be different for each site. The best way for you to tell is to load the page 10 times clearing the browser cache after each time and average out the page …
Sorry, no. It all or none.
No, but, it is possible to use a SiteShot as a backup if there is not an image/logo. You would use the image_fallback=’siteshot’ shortcode option which is available to many of the premium templates. Setting this option would display the SiteShot only if a image/logo was not available.
SiteShot uses a WordPress.org service to provide the screenshots of websites. When you view your directory, SiteShot senda a request to that service. That request enters a processing queue. If that processing queue is busy it can take a little time to get a thumbnail. In my experience though, usually the thumbnail is available within …