There seem to be two questions:
1) "it appears that there is the potential of data
flooding in and compromising my current Salesforce structure." From my experience, you can control what fields sync between Marketo and Salesforce through the page layouts for the Marketo Sync user. Marketo should have read write access to to fields on campaign, leads and contact. but it will only have read access to other objects the administrator allows. You can get a marketo sandbox to test out this in a dev org from Salesforce or a salesforce sandbox. On the fields that are allowed to sync between the two systems, the information syncs as sysmod dates are changed from either side.
2) "Are there ‘best practice’ ways to contain
this information by segregating information before giving to permission to add
to my Account date fields?" Can you clarify what you mean here? I think you mean can you not allow marketo to see everything in salesforce? yes, just limit the profile for the marketo sync user and limit field level security and on page layouts.
There is quite a bit of information on the SFDC sync in addition to Lindsey's suggestions:
- Every 5 minutes after first sync
- Marketo User - yes to what Lindsey said, but if you have a complex setup or wish to block certain fields or objects from syncing (or just some records), you need to define this at the Marketo user Level. There are A LOT of threads on this.
- Docs on first time setup: https://docs.marketo.com/pages/releaseview.action?pageId=2360372
- Keep in mind you can also use Admin > Field Management > Field Blocking to prevent data from being overwritten in both systems and under certain situations.
- I suggest that you speak with your SFDC Admin and your Marketo Rep to resolve further questions. You can also email me directly.