Multi language site

I have spent the whole day reading and researching this topic and most info is old and some is just confusing so I am hoping that I could get a quick answer to the question below.

I currently have a site for a client in englis – single install on mydomain.com. Directory tree is ./mydomain-wordpress.
My client now want to add an additional language to their site.
What I understand from all the reading is is run a seperate install in a subdirectory. mydomain.com/language2 and if more are needed later to the continue with mydomain.com/language 2 etc.
What I want to know is…
1.Is this bets and easiest way to do this?
2.To link the one install to other through a language button 0 is it as simple as just hyperlinking the full address mydomain.com/language1.

I know this is a long story but want to make sure before starting this project.
Thanking you in advance.