1) Alexander wouldn't actually be anymore effected by flashbangs then any other normal person, of normal vision, as his eyes work more like a Felines(in this case they are not feline in distinction though) and actually dilate accordingly for light at the present situation. (I.e. They open or close and change the reflective aspect inside his eyes to adjust in a natural manner to light, just like a feline or other nocturnal low-light vision using animal.)

2) The grade of a weapon, and whether it is homemade, stock, military grade, etc, etc, etc, etc, would all depend solely on where the weapon's point of origin was during the event, or after the event. Plenty of weapons fill homes in the US, we have guns gallore in a personal aspect to be honest and they can be found anywhere. Doomsday prepping bunkers, homes, vaults, safes, warehouses, etc, etc, etc, etc. So, you can pick up just about any type of weapon in nearly any kind of condition you want in this Rp, so long as you have a point of origin for it.

3) For an example of something possible, the Gun Runners in Fallout: NV were originally raiders who stumbled upon a plant for firearms manufacturing, it wasn't operational. It did however house all of the blueprints and know-how books to teach them how to make a plant of their own. This took only around fifty years for a large scale business in a post-apoc setting to begin operation.

4) Thirty Years Post Nuke can actually survivable, it all depends on a few variables: Placement of nukes, spread of nukes, radius and caliber of said nukes, and how thoroughly of a job said nukes did on their targets. Widepsread nukes can actually leave pretty wide zones untouched by the mass of the explosion with only minute effects left in remnant which in turn can create the Chernobyl Effect. (I.e. There are hit and miss hot-spots and livable sectors.)