Well, a low mount might work for some kind of scope, because the focus point of the scope will be really far infront of the gun, so you won't "actually" see the front sight (I don't know about the rear sight getting in the way of the scope opening), but for an aimpoint which have no magnification, it would be better to use a high profile mount.
For the silencer it's all stock (really for a stock one) and the foregrip is plastic, but some kind of rubberised, not like the rest of the gun.
You can choose to go with a low mount, in this case, the red dot of the aimpoint will appear just at the tip onf the front sight, so I think it can be nice too if you don't mind the ring around it. That's the case with my M4, I have and aimpoint with a cantilever mount, and the aimpoint is perfectly aligned with the front sight.
