A realy stupid question

[Schraddel]

Lester,
that depends on the outputs of your decoder. For such an steam action what do you really need?
At first a decoder with an very good BEMF funtion, as some locos are a bit nasty especially on switches and tight curves. BEMF has the benefits to guide them at a constant speed on this passages.
Second, light functions:
- front light
- back up light were appropiate
The luxury function is rule 17

A luxury function is cab light. Sometimes the cab should be stay dark due poor or nothing detailing in it.
But sometimes:

You will be delighted in more than one manner

Here i used a simple ESU Lok Pilot Basic decoder. It offers a good BEMF device and only 2 fuctions:
Function 1, is the headlight and back up light. They are automatic changing to each direction.
Function 2, here i have wired the cab interior light.
That was it.

You don't need an expensive decoder with many, many outputs which can manage the all the lights of a commercial house on Christmas time.

Every decoder comes with an wiring diagramm and i give you the good advise to RTFM the manual.