change to www from naked domain impact on seo

I have set up my website from the beginning to be used without the www, ie 'naked', with the following command at .htacess and everything is working fine.

RewriteCond %{HTTP_HOST} ^www.soeezauto.ma [NC] RewriteRule ^(.*) http://soeezauto.ma/ [R=301,L]

Now, I have placed the website on Cloudflare for optimization reasons and it seems that they are only able to handle www domains ( if you come through a partner host, which is my case ), so I need to change my domain to work as www.mydomain.com

My main concerns are:

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  losing INDEXATION

  
  


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  losing HISTORICAL DATA on Analytics/Webmaster

  
  


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  make sure all the web pages I have out there without www will show normally when I change to www.mydomain.com

  
  

This is what I found so far:

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  in Google Webmaster in website settings, favorite domains, it is marked as not defined, meaning neither mydomain.com nor www.mydomain.com are selected. So, should I leave as is or should I choose www.domain.com ? Or is it something else I should do?

  
  


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  in Google Analytics I found this article. Is it fine to do like that?

  
  


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  in .htaccess RewriteCond %{HTTP_HOST} ^.mydomain.com [NC] RewriteRule ^(.*) http://ift.tt/Rvl2Tu [R=301,L]

  
  

Also, I read in this question, that I should REDIRECT ALL OF MY WEB PAGES to WWW via .htaccess. Is that the case? I have about 4000 pages out there. It will slow the server down quite a lot I believe to have such a huge .htaccess.

Will that work? Last thing I want is to mess this up and lose data/indexation, not to mention have the site inaccessible to my visitors.

I appreciate any guidance.

Thanks