Does Marketo Sales Insight just show up once you sync Salesforce with Marketo? What other features of Marketo will just "show up" once the sync is complete?
No, MSI will not magically appear when you sync Marketo. It is a separate package that needs to be installed in Salesforce. What will work with the Marketo package installed is synchronising data on your leads, new leads being sent from Marketo and campaign synchronisation, depending on the settings of your integration.
Kind regards, Katja