Today one of my friends has sent me a template file to edit, it's a '.xml' file. My friends site is dynamic. But I have never edited or worked or created any template. So, I am in a great confusion and I have many questions. So I think you would be able to help:

1. What is template? Is it generated by a software or created by hand-coding?

2. Do I have to know PHP or Server Side language to edit templates?

3. There are some things in that XML file that is not related with HTML or CSS or JAVA. Some lines are somethings like:
<b:if cond='data:blog.isMobile'>
<meta content='width=device-width,minimum-scale=1.0,maximum-scale=1.0' name='viewport'/>
<meta content='width=1100' name='viewport'/>
4. He has got comments in his website. If I edit the CSS of the comments section, is it enough. Because comments only appear when anyone posts it.

5. There may be something that uses the template while generating dynamic pages of the site. I want to edit the whole site. So do I have to care how that program uses the template? Note that my friend has only sent the XML file and nothing else.

Above all, I think I don't have knowledge about template. So if someone explains template to me, I hope I will be able to solve theses probs myself.