Azure Active Directory dynamic membership for groups in a hybrid setup

We're very interested in the new public preview functionality for Dynamic Security Groups but I have a few questions.

1.  We are set up for Office 365 in a hybrid environment (AD/Exchange/Lync) with a migration to SharePoint being planned (SharePoint isn't hybrid with any on-premise SharePoint environment). Can we still use the Dynamic Security Group functionality without breaking anything?

2.  With these security groups being created in Azure AD, do they replicate back to on-premise in a hybrid environment and can they be used on-premise?

3.  What are the licensing implications of using this functionality? Is it just one premium license per engineer who would create these dynamic groups or is it a premium license for any user who is a member of the group?

Thanks in advance

Michael