Jenkins- Best Practices for Security

Hello Jenkins Users !!

I'm a Jenkins Newbie and from a security background...

1. I'm wondering what kind of System-level hardening must be done on
Jenkins Masters server instances? Also on the slaves machines ?
2. Can an admin of Jenkins CI get SSH keys for the communication with
slaves using the jenkins script console?
3. Is there any good blog/book/article on Jenkins best practices for
keeping them secure.

Thanks....

Regards,
Rahul