imranbot I would like to send an automatic notification to the user whenever the ticket is resolved or closed!

Status changes do not trigger notifications/alerts. Your Agents would have to use a canned response as a reply, and then select the appropriate status to change the status to.

imranbot secondly I would like that if a client writes to us in Spanish the email is sent in the same Spanish language.

You would create a Department that uses a different template for each language that you want to support.

So if your primary department is "Help Desk" this would be your English.
You create another department called "Mesa de ayuda" which you assign your Spanish templates to.
Transfer the ticket to the appropriate language Department combo, and then reply.

@imranbot

You would have to customize the code to change the Favicon.

Cheers.