If we talk RDSCALS, then the licence server will 'borrow' them for user/device that connect to any server that got the RDS service role.
For Windows CALS the calcul is not the same. You need a CAL per resource (user/device) domain wide. Each CAL cover the use of all your users on your domain. Just make sure you have the correct's one. (If you have 2008R2 user CAL, those users are not entitled to use 2012, 2012R2, 2016, etc.. ressource in example.)
Yes, you install it like on a domain controler, and everything is fine. The only restriction you have is you need CAL for the latest Server version you have inside your park. (like 30 2019 users CAL if you run on OS 2019 and less)