Not compatible?

I don't see how it could NOT be DCC compatible.  After all, track is track.  The turnouts might not be DCC-friendly (I have no idea), but that's not the same thing as incompatible.

As for the crossover, you'll need to isolate the reverse loop and put a polarity reversing switch (manual, or automatic, depending on your budget) in the leads to it.

what is the difference

what is the difference between not compatible and not DCC-friendly?

Incomatible vs. unfriendly

Not compatible means that it won't work.

Non DCC-friendly turnouts will still work, but there is an increased chance for shorts to occur.  Check out Wiring for DCC to learn more.  Basically, a DCC friendly turnout has the points at the same polarity as the associated stock rail.  Non-DCC-friendly turnouts have both points at the same polarity, and a metal wheel could bridge the gap and cause a momentary short.

Wrong

Unitrack is fine with DCC.  The thing with the turnouts is they are power routing, so it only powers the side that the points are thrown towards, but it still works with DCC.  

Insulate your frogs

In that case, make sure you put insulators beyond every frog.  Otherwise, if there is a feeder anywhere downstream, you could have a short.  It's not bad practice anyway, but it's mandatory if you're going to use a power routing turnout except in the case where the only feeders are at the point end of the turnouts.

Hi there, I spent some time

Hi there,

I spent some time working with N scale Unitrack and came away very impressed with the quality and ease of setup.

Kato #6 is power routing and #4 is actually selectable routing/non-routing via the screw inset on bottom side of the turnout fixture.  Kato unitrack is compatible with DC & DCC.