Sql Server 2014 update path advice
You actually want to keep up to date on service packs in SQL &lt; 2014 as you won't get support after awhile if you don't.

The support policy can be found here.

Generally installing Service Packs is safe but for any production system please make sure you have a strong backup model in place and hopefully a test environment to simulate all changes for production ahead of time to validate that they work.