yeah, they're all called ATIV books now.
$1,599 is the best price i've seen for the i7/8/256 ATIV 9 Plus, so if you're cool with the touch screen, it probably won't get better than that for a while. once the MS Store sells out of a model, they never seem to carry it again. it comes with an N wifi card, not AC.. but you should be able to upgrade to an AC card on your own if you take off the back.
i've been waiting for this new ATIV 9 with Haswell though because of the non-touch matte screen. it's still an excellent FHD display where you can work with it under any light conditions, which is key for me. i'm not thrilled with the $1,399 price for the base i5 version though, so i might wait until it's been out for a bit to see if it gets discounted by $200 or so.
yeah, that newer model of the 9 Plus isn't much of a difference.. basically adds the TPM chip. Samsung will likely do a bigger update of the 9 Plus again in 3 or 4 months with an AC card, a better graphics card, and maybe something else. but yeah, the waiting game gets very old.