I have a Keltek sub 2000 9mm and it’s great to shoot it’s just hard to get my eye down there because it’s a straight stock not like this Ruger which is on a rifle stockGot this a month or two ago. It's a blast to shoot, although it really is kinda useless! What I mean by that is it won't do anything a AR won't do better, but like I said, it is a lot of fun, and that's what it's all about, right?
There is a Ruger tip video on YouTube about disassemble and another on reassemble. It is fairly simple and you should have no problem. I am not sure about the torque wrench requirement but to me it would be more for insuring snug securement without over torquing the screws. The iron sights are mounted on the take down barrel and the rail is mounted to the receiver. I use a red dot on mine and have noticed no problems with point of impact after cleaning. When you assemble the take down everything should line up the stock and fore end are just screwed on and should not affect the accuracy.
It is after all is said and done a 9 mm pistol caliber, I only have mine sighted for 50 yards. It is much more accurate that my old arms can give it justice. But it is a hoot to shoot. Go for it you can not beat the price and quality.