River Defense

[J6A]

First, a possible rules contradiction (4e).  The rules say that units assaulting across a major river have a -2 column modifier, while the TEC doesn't limit it to major rivers.  Which is correct?

The second is more of a practical question.  I'm playing a scenario from First Axis that has the Slovaks set up "on or west of the river."  Does this mean they can set up in river hexes, and are assumed to be on the west side, or do they have to be in the hexes behind the river?  It seems like setting them up on the river lets them (possibly, depending on the question above) benefit from the column shifts against the attacker in an assault, while defending behind it gives them the +1 column for shooting at units crossing a river.  However, I'm a bit confused.

Oh, I guess related would be whether the -2 column applies to a unit assaulting from a river hex to a non-river hex.  If that's the case, then it's pretty obvious that units would want to be behind the river.