You should be able to update the dates and fields in SFDC if you have permission to so.
Is you marketo program and sfdc campaign sync'd/connected at the moment? That might cause some problems in editing it.
They are currently connected. Do I need to disconnect that to update the content in SFDC? Shouldn't that information automatically transfer from Marketo upon the initial sync?
Date and description will be fine.
You might want to review the advanced statuses and make sure they match up with the program statues.