Ruby on Rails and Microsoft SQL server

I am asked to build a website with ruby on rails using a SQL server backend. I have only built sites with sqlite and postgres so I am a bit unsure. I did some digging and found a gem I can use.

activerecord-sqlserver-adapter http://ift.tt/VHGT00

1) I am wondering if I use this plugin, does it mean I can still set up models and using active record searches such as where()

2) If users are pre created in the SQL through a EPRS system, will I still be able to integrate devise with that?

3) They are going to give me a bak file for the SQL server and asked me to set up my own sql server on my mac during the development phase, is this possible or do I have to pay for a microsoft sql server license to do this?

Thank you very much in advance, any help would be deeply appreciated. Thanks again.