How will “windows based” authentication work in MVC web application, if users access the application from outside the company intranet

I have the following architecture:-

• ·        Active directory server

• ·        IIS which will host asp.net MVC

• ·        Both the Active directory and the MVC web application are inside our company intranet.

• ·        I set the Asp.net MVC authentication type to be windows based.

But I have these questions:-

1.  If our company employees tries to access the asp.net MVC web application from their home using their personal PC; will windows authentication work?
2.  If the above answer is Yes; then how they will be typing their usernames,  Something similar to username@ domain.com ?
3. According to my above requirements, should I consider having form based authentication that is connected to AD? Instead of using windows based authentication?

Thanks for any help and advice

Best Regards