I'm in the process of setting up a large digital layout using K track. In reading about the Marklin Central Station - CS3+, I'm finding a couple of questions I can't get answered. I did purchase the Marklin "Controlling Digitally with the Central Station 3" which helps a lot (although it's written assuming you will use C track). However, I'm not getting a couple of things:

1.). Do I need to use the K83 decoder with (4) turnouts, or can I use individual decoders at the turnout, then connect directly to the track (and by-pass the k83)? If it's either/or, what is the benefit of using the K83?

2.) What is missing in running trains using just the CS3+ once the layout is operational? From reading about the CS3+, it appears to let you do everything - track diagram, programming routes, etc. Obviously it's not doing everything since others on this site are using the CS2/3s AND other operating systems such as Traincontroler.

Those individual decoders are offered for C track. They fit under the road bed of C track and are useful for temporary floor layouts.
C track decoders can also be used with K track, but since they do not fit under the road bed, there is no real advantage.

A k83 is one decoder chip with four output stages, the individual decoders only have one output stage, but still need a decoder chip. With k83s you can safe a lot of money.