Read sharepoint external-list items

Question

I am working with sharepoint 2010. I have an external list. I need to retrieve the list items from the external list for which i am using the following code below.

SPQuery query=new SPQuery();
query.ViewXml=list.DefaulView.SchemaXml;
DataTable table=list.GetItems(query).GetDataTable();

Question 1: The above process consumes a lot of time and finally shows the message while debigging that "Function evaluation disabled because the previous function evaluation timed out" Can anyone tell me why does this happen?

Question 2: I use the property HasExternalDataSource in order to check whether the list is en external list or not. But this property works in sharepoint foundation 2010 only. Does this property can be used in sharepoint 2010 server also?

Regards, Sharmila