A friend has a large quantity of Kato track (unitrack?).  Will Bachmann locomotives,engines and rolling stock run on Kato track and a Kato transformer?  Don't want to buy something that will not work with what I have (all Bachmann and EZ track).

can one place to engines on the same track or does one have to be a "dummy"?

Most the of sets I see have only four cars.  How many cars can one add comfortably with minimum inclines in the layout?

I am brand new to the hobby.  Have seen engines for sale marked "analog".  Am not sure if any new set I purchase will be DCC.  Have one set and it does not state analog or DCC.  It is NIB Yard Boss but could be older.  Also, will all Bachmann N gauge rolling stock (non locos) fit on the e-z trac systems.