Planning for RDS Licensing installation

Hi

I am planning to install new RDS server on my environment and want to know best practice ,below is environment and question's answer which I looking.can anybody help me sort out this.

1. two Win 2008 R2 RODC server with 8 members and has citrix application.

2. which CAL do I need to use per user or per device , in case of per user configuration if RDS server goes down will my user will be able to connect server.

3.in case RDS server goes down ,can I use the same license in another server and activate.

4. if I purchase 200 lic ,can I divide into server means 100 in one server and another 100 in another server.

thanks

Rakesh

Regards Rakesh Behura