Installed multisite, Plugin MSLS, do I still need create custom page templates?

Hello everyone,

I would like to do something that I thought would be very common, yet I don’t really find a tutorial that is useful for me. (I don’t need to have a bilingual wordpress installation where the admin panel is in different languages; I don’t need anything translated for me, etc)

I have made a custom theme from a stripped Twentytwelve; with very few additions such as registered some menus in functions.php and a few custom templates for the pages and the blog page. Now because I need this site to be bilingual, I transformed the site into a multisite, and created the spanish site next to the ordinary english one.
I also installed the plugin Multisite Language Switcher, after having read numerous tutorials and suggestions on this. But actually, I’m still not sure if I can make use of this plugin?

In my template files I have some english words, such as “Read More” after the post excerpt in the sidebar. The entire footer.php contains english language. And what concerns the navigation menus; I guess I can just register another set of menus in functions.php and enable them in the spanish website’s admin panel?

This all boils down to three simple questions:

1, Do I need the MSLS plugin?
2, If I do need MSLS, do I still have to create custom templates for the spanish language? (for example, the footer.php)
3, If so, then what do I name them? My template files all have names such as page.php, home.php, footer.php and so on; as these names have a place in the loop; so if I for instance create a copy of the footer , I guess I can’t just name it footer-sp.php?

Maybe the solution for me would be to make a child-theme instead?

I would very much appreciate if anyone could point me in the right direction.