For # 1, the simplest method to use would be to make the form that the staff enters the details a data entry form so they would only be able to enter via that form, not edit. The video Disallow Editing Data will show you how to use this method.

For # 2, are you trying to get the native datasheet view to update (i.e. when you open a table from the navigation pain, it opens in datasheet view), or are you wanting to refresh/requery the data in a form after making updates?

These videos will show refreshing/re-querying form data:
Immediate Refresh
Refresh v Requery
Requery in Place
Requery Subform

In order to requery a native datasheet view, you would need to use a macro or vba in a button to requery it if it's open.