Limiting registration access

Hello,

I would like to enable colleagues from my organization only, to be able to self-register once they click on a shared link. Is this possible to conficure? 

Also, on the landing Customize Self-Registration Page, I noticed that some info are in French (or English for my colleague). Is it possible to have it bilingual or what decides of the default choice of language for the user?

Thank you for your help!