The weapon swap is pretty simple. Just try doing this:
Condition:
Num1 key is pressed
Or
Num2 key is pressed
Action:
Set scene variable *Weapon* = 1
Or
Set scene variable *Weapon* = 2
And then...
For your first weapon:
Condition:
Scene variable of *Weapon* = 1
Action:
Hide Gun2
Show Gun1
For the second weapon:
Condition:
Scene Variable of *Weapon* = 2
Action:
Hide Gun1
Show Gun2