FWIW, I have a TA01NSN and found it a little bit easier to zero than the TA31F my buddy has. The crosshairs of the NSN line up perfectly with a regular grid target. I didn't think the TA31F was very hard to zero though, they are both pretty simple, just use the very tip of the chevron. Oh and just FYI they should be zeroed at 100 meters, not 100 yards (or 109 yards, roughly). This will make the BDC more accurate, though not 100% as it is not a guarantee of anything, just an estimation for hitting man-size targets.
Color doesn't matter but I prefer red because Aimpoints and EOTechs are red and that's just what I'm used to when it comes to illuminated reticles and electronic sights.