When I considered the P99, I was aware that there were three variants. Since I had spent years using Glocks, it was a big issue for me to get one that had a comparable trigger. The P99 QA will be a reasonably smooth transition if you're a Glock shooter. The trigger is gritty for the first 500 rounds so be patient with the break-in process.
As Catbird stated, military version denotes that the frame is green not that the trigger is QA. So far, they have not released a military (green frame) version of the P99 QA.
Regarding your night sights question, this link should prove helpful:
http://www.jimcostanza.com/home.night_sights.html
Last thing regarding the P99 making in-roads... I have personally turned on four friends to the P99. Two of them are people who are long-time pistol shooters. All of them love the gun, most citing the ergonomic grip. One guy with big hands loves the fact that he could change the backstrap to something better for him. Another who is a former 82nd Airborne armorer regards the P99 as a pistol that is likely to replace the current generation of military sidearms since it is superior while also remaining "Joe-proof."
I think the gun is making in-roads slowly for several reasons. When the pistol first came out, I recall it being more expensive then it currently is. Also, I never saw one as a range rental. Another problem was that I had never seen the variants (P99QA and P990) at a gun store. (I bought the P99 QA after firing a standard model, figuring it was worth a role of the dice for the trigger as described on the Walther website- Fortunately, I was right.) Another factor that the P99 has to struggle against is the current entrenchmment of the Glocks. Both Federal and local law enforcement agencies bought Glocks in large numbers. The result was that a lot of people who wanted the guns that cops used. (In the late 80's it was the 10mm since the FBI used it. In the early 90's it was the Beretta 92 FS since the military and LAPD used it. Now it's Glocks since they are they are virtually standard issue for law enforcement.) -These people already have their guns.
-That said, I think the P99 will eventually be a leading seller. The P99 converts everyone who I've seen use it by its grip alone. Its accuracy is phenomenal, easily rivaling HK's. If there were more of them at the ranges as rentals (both the standard P99 and the P99 QA), they'd win a lot of converts.