Thanks for the information about the performance dashboard, its reports are very useful for tracking down a variety of performance problems. They work off the underlying DMVs, to explore these in further detail please see my MSDN article here: http://msdn.microsoft.com/en-gb/magazine/cc135978.aspx
The main purpose of this current SQL Server Central article was more about how to view potential performance problems in code that is already running on the server. However it seems many people are interested in missing indexes in particular. I would suggest you look at the MSDN article mentioned above, it should have all the relevant code you need to investigate the missing indexes in greater detail, including details of how the estimates are made.
As to your question about the ‘iscom’ column, it may be that the column is always retrieved from the table, hence instead of doing a key lookup (bookmark lookup), the optimiser suggest having the column INCLUDEd with any index.
One thing to note about the suggested indexes is... they really only apply to the current SQL statement, i.e. they don’t take into consideration all the other SQL that might determine if this index should really be created.
Hope this helps