Best way to sync contacts

Currently - our company uses Google Workspace with Google Contacts to keep contacts up-to-date (i.e. add new contacts). We then import the Google Contacts to Mailchimp, and run email marketing campaigns. When using Mailchimp, some contacts unsubscribe.

We want to have up-to-date contacts in Google Contacts, MailChimp, and Copper. Importantly - we do not want to email those that have unsubscribed (i.e. if we shift to Copper for email marketing in the future). 

We are new to Copper, and want to ensure we set things up correctly from the start. A few questions:

1. Should we import contacts into Copper from Google Contacts, or from Mailchimp? My understanding is we should from Google Contacts/Google Workspace - so we also get all the prior communication (emails, etc.) as we communitate with customers daily through Google Workspace
2. What order should we import contacts to Copper (i.e. Google Contacts first, then do the Mailchimp integration?)
3. Should we set-up 1-way or 2-way syncs with Mailchip and/or Google Contacts?
4. What will be the best way to update contacts in the future (i.e. use Copper as master or Google Workspace?)

Overall - I’m a bit confused on the best way to set-up and keep our contacts across Copper, Google Contacts and Mailchimp up-to-date. I think it may make sense to make Copper the main place where we update contacts, and then to have those contacts update in Mailchip and Google Contacts - but I am open to suggestions on the best set-up. 

Any advice appreciated!