Which sitemap file should I submit to Search Engines?

Submit the dynamic version sitemap file to search engine. Please note you only need to submit the sitemap index file. All other sitemap files are automatically fetched from this sitemap index file.

SInce this is dynamic, whatever changes you do to your website are automatically refected in these sitemap files. Thereby you would not need to resubmit sitemap files everytime.

What is the use of Raw XML files?

RAW XML files are generated from the dynamic sitemap index file. This is just an additional option and you actually would not need these files. Therefore you can always skip generating raw XML files. These raw XML files are helpful only in some special cases where you might need the XML file or when your website has lakhs of products and server gets overloaded most of the time. Only in those cases you can generate these raw XML files and submit them to search engines to crawl. 

These files doesn't use database and are static files and needs to be generated manually every time when you add any product or category or any page to your website.

What is ping Google or Ping Bing buttons?

Once you generated sitemap, you can always notify Google or Bing by clicking on this button. 

Please note Google Search Console (formerly Google Webmaster) account is highly recommended in order to monitor the status of your sitemap. Similarly for Bing or any other Search Engine Webmaster tools.

Can these sitemaps only be used for Google Search Engine?

Almost all search engines follow the same rules when it comes to XML sitemap and hence you can use these sitemap to any desired search engines. Since Google is the most popular and most used search engine worldwide, the extension is developed based on the latest standards of Google.