You can use this to try to get row count:
public Int64 GetRowCount(string tableName)
{
object value = ExecuteScalar("SELECT CARDINALITY FROM INFORMATION_SCHEMA.INDEXES WHERE PRIMARY_KEY = 1 AND TABLE_NAME = N'" + tableName + "'");
if (value != null)
{
return (Int64)value;
}
return -1;
}
If that fails, you can use "SELECT COUNT(*) FROM table"
Space used is not available, but you can estimate based on this: http://support.microsoft.com/kb/827968
For data comparision, the best approach would probably be to migrate each sdf to a SQL Server Express database, and use a SQL Server Data Compare tool