The Census-provided GIS data is in a Lat/Long coordinate system. Your data must be either projected or imported using appropriate layer projection settings.
Support for Census Tools for ArcGIS is available from Citygate GIS, who provides several levels of onsite phone and e-mail support. Additional information can be found at www.citygategis.com/censustools.
The main focus of the LUCA program is addresses. As such, any data source (geographic or tabular) which identified all current residential addresses in your jurisdiction would be of benefit. This type of data may include tax assessment data, 911 databases, water and sewer customer databases, and so forth. Other data which could be of benefit to the project include GIS road data as well as satellite and/or aerial photography.
The BAS program focuses on the legal boundaries such as counties, towns, and cities. Local GIS data depicting these boundaries can be used with the BAS program.