Availability of on premise distribution groups during on premise outage

[dtd646]

I run a hybrid exchange environment with Exchange 2016 and Exchange Online.  I have a maintenance event coming up with my on-premise exchange server where it will be offline for a few days.  I have 2 questions:

1. My on-premise exchange 2016 server still currently houses all my distribution groups that are internally and externally available.  All of the user mailboxes are in Exchange Online.  If I shutdown the Exchange 2016 on premise server, will the distribution groups still work if my hybrid setup is configured properly?
2. If I flip my mail routing to flow through Exchange Online first, will exchange online deliver messages with a destination for the on-premise exchange server?

Thanks in advance.

[#2]

It depends on how you are routing the messages and whether the groups are synchronized to O365. If the message is handled by ExO and the group is represented by a recipient object there, it should be expanded/resolved to the individual recipients and delivery will work.