I´d like to add Point Blank shot and Ragnefinder to this question.
Accurate weapon is written as "having no penalty at short range", while Targeting scope and Far Shot are written as "Reduce the range category by one".
1) Does that mean that they can be used in conjunction with PB shot? (the scope and far shot, I mean - accurate weapon only eliminates the penalty, it doesn´t change the range category so it´s out of question)
So PB shot + Scope OR Far Shot = "penalties" +1/+1/-2/-5
and all three of them = +1/+1/+1/-2
2) Rangefinder is written as "the weapon with rangefinder takes no penalty on short range, and it doesn´t stack with Scope". I´d say that it only stacks with Far shot, then.
It eliminates the penalty in the same way as Accurate weapon, and you can´t eliminate the penalty twice.
It doesn´t change the range category, so it can´t benefit the PB shot.
And it is written right in its dfescription that it doesn´t stack with Targeting scope