Getting to know SFMC

What is SFMC connector?
SFMC connector connects your Salesforce and your MailChimp so that you can run your marketing campaigns more effectively and easily. It ensures a smooth flow of your business information between your CRM and email marketing software. It brings back your campaign statistics to your Salesforce and updates your Salesforce. You can populate your MailChimp list from Salesforce using this connector.

What exact Information will flow back and forth in every Sync ?
From Salesforce to MailChimp:

Syncs Leads/Contacts of Salesforce to the MailChimp list of your choice.

Apart from first name, last name and Email Id, you can transfer information residing in
10 other fields of your Salesforce Leads/Contacts to MailChimp

From MailChimp to Salesforce:

The information about status of mail sent to each (bounced/ unsubscribed/opened, etc)
Will be shown in your Salesforce

How often and when do the Syncs happen ?

You can Sync your data any time / every 12 hours.

Since its your data and your business, you should have a complete control over it.
You can Choose the timings when you want to sync your data every day.

Is there any limit on number of records I can process using SFMC connector.
No. We dont limit the number of records.