Is there a difference between DCC and analog lighting in passenger cars?  Are the cars interchangeable
between the 2 systems.  It seems that som of my cars will not light up on the analog portion of my set up. 

Is there a way to converts EZ track to reversing track??  ie: the non-standard sizes such as half track straight and curved
and  other short pieces?  Also full length curved other than the 18" Radius

Can sound be added to this unit?  What is degree of difficulty?  What parts/tools are needed

The couplers on the on30 passenger cars keep disconnecting from each other and from the engines.  Is there a solution??