Use the 2 points option and then select the mid points of the 2 angled lines to create the vector, then slect the midpoint of one of the lines to position it.
How to correct the angle ?
A lot of times, I will create a sketch in the view I am projecting, or cutting the view from. In this sketch, I'll create my "hinge line". Create my 'flipped' view. Then I can use view dependant edit, to hide the sketch.
It can be confusing for others, if they don't realize how the view direction is controlled, that being the caveat.
"Is there also way to shorten the "section leaders" ?"
Open the section line settings and change the arrow line length value.
I do not have access to NX 9 so this is NX 11, but I think the perpendicular section line( angle to XC) should work in NX 9 however the control of the length section line itself i think came in NX 10 and I suggest you look at DaveK method for that.