Q. Can SharePoint search crawl external data?
A. One of the capabilities of SharePoint search is that it can crawl external data. For this you need to create a new content source of type Line of Business Data and configure search for your BDC service. You learn more about SharePoint search in Hour 18, “Introducing SharePoint Search.”
Q. Is it possible to upgrade from Business Data Catalog of SharePoint 2007 to Business Connectivity Services?
A. Yes it is possible to upgrade from Business Data Catalog to Business Connectivity Services. You can find more details at http://technet.microsoft.com/en-us/library/ff607947.aspx.