Question 1/ None. The sync just updates records on both ends, but does not consume data storage, excepted the one used by leads and contacts. Of course, news leads are being pushed, but. There is 2 exceptions though:
- automated tasks created from Marketo activities (set in admin -> salesforce). These consume a lot of space and can jam your SFDC data quota. recommended to disable all these.
- Campaign membership that are created when you sync Marketo programs with SFDC campaigns
Question 2/ Use SFDC reports that leverage the "User created" = Marketo sync user field in SFDC. Run these reports on leads, campaigns, campaign members & tasks (which are the records that can be created from Marketo). Contacts, accounts, opportunities can only be created in SFDC.
Thanks Greg! That answers my questions!