2.  I want to be able to control what values are going back into the database.  Sometimes a NULL means different things than a "" string value or a 0 decimal value.  Is there some way to control how it puts it back in, but always return it with the replacement value applied?

2) There is an option for returning a replacement on null and setting null on the replacement.  If you use "" for the replacement and try to set that as the value, the property will set NULL back to the database.  However if you want to differentiate between NULL and "", then you'll most likely have to use the CurrentRow property on the business object to set null values back.  bo.CurrentRow("field") = DBNull.Value will do the trick and bypass the strong-typed property.