Shared Mailboxes in Hybrid Environment

I have an hybrid deployment and need to move shared mailboxes. Upon moving, they shall appear as type- SHARED. My question is 

1. I have an Hybrid setup, I want to move a shared mailbox residing On-Premises to Cloud Organisation. All users assigned to the shared mailbox with "Send As" permission are on premises users.
   1. What steps shall i perform?
2. Can i have shared mailbox in
   1. Cloud organisation 
      1. with "Send As" permission for users belonging to both On Premises and Cloud at the same time? can both my on - premises users and cloud users can use the mailbox?
   2. On- Premises Organisation
      1. with "Send As" permission for users belonging to both On Premises and cloud ? can both my on - premises users and cloud users can use the mailbox?

Any advice on how to move shared mailbox is greatly appreciated.