Beginner Anim Blueprint Questions

SO in UDK I made different Anim Sets for each weapon the player could carry. When the player swapped weapons I changed the skeletal mesh’s AnimSet.
I presume in UE4 we can change the Anim Blueprint on the fly for the mesh so it will update when I change weapon?

Would the Set Anim Instance Class node do what I want?

Also, my game is a Iso metric twin stick shooter. If I press the right stick past a threshold I want the characters arms to move from hands down by his side to up aiming a weapon.
I’m wondering if it would be best to make a 2D Blendspace, so I have Speed and Aiming(on/off) variables set up, and the mesh animates between them. Or would I be better making a new state in the state machine?- that transitions from idle/walk/run to idle/walk/run whilst aiming?