Upgrade from SEP 12.1.6 MP10 build 7445 to 14

Hello,

I am looking to upgrade our current SEP server from version 12.1.6 MP10 build 7445 to 14. Below are some question. Hoping you guys can help out. 

1. Can I upgrade from my current version directly to the latest version of SEP (14.2 MP1)?

2. Will my version 12 clients continue to work on SEP 14 and up?

3. Will clients on version 12 auto update to version 14 or is that something I have to kick off or enable?

Thanks,