2 armatures from blender to Unreal Engine?

Hi, I would like to solve some of my doubts this 3 question is part of rigging process , exporting process and take care in the perfomance for a game.

let me introduce , I have a 3D model with differents types of guns (rifles , pistol, shotgun) something so trhilled, something so common in this times . Every weapon has their own bones and this bones are parent to themselves , but they are bones appart , they not share the 3D character body’s armature ( they are on different armature or rig ) , the main character has his own armature and about this ,the questions began .

1 - it is a good practice to have 2 different armatures one for the main character and the rest for different weapons ? you know , for every “action” ? (consider the actions as animations) , such as “reloading” , “running_Wgun” , “standPos” , “Idle_Wgun” “dying_wthGx” “Dying_withGy” , “Grenate_trhu” ,etc.

2 - I ve created 2 armatures thinking of using classes or blueprint , or some good hand-maded script to change different weapons , with “1” select melee and make a pose when you press 1 , then if character pressed 2 , he brings a Pistol , and the pistol draws in the animation , (so if you click you fire , etc. I make this question thinking in performance or code’s easy way ) .

3 - Does exist any limitation for exporting IK from blender to Unreal? specially in this kind of purpose (character’s with guns) where reloading is a common action for every single weapon but at the same time , the hand is capable to do differents things , via the “influence” ( for example, create keyframes in the contraint display’s value , I meant “child of contraints” and in the option of “child of contraint” you can set keyframes and manage the slider to 0 to 1 to flow the animation , specially for Holding objects, the powerful of this).

4 - There are tons of boring tutorial with 2 hands holding a weapon , it draws , fire or reloading, but those process is living just in blender and the output , but not for a real exporting where you can suffer something with bones , I would like point of views about bones, armatures, influence ,constraint in this process , short and simply so I can continue reading and put it on practice. Thx.