How do I do a few things like

Development Programming & Scripting
1

There are punch and double jump tutorials on Unreal Engine Youtube channel, zoom community tutorials Youtube and forums, weapon system tips/tricks in the forums.

2

Crouch, zoom, switch weapons, punch, and double jump. You don’t need all at once.

3

Hey,

Crouch: Unreal Engine 4 Tutorial - Crouch - YouTube
DoubleJump: Blueprints - How to Double Jump - Unreal Engine 4 - YouTube

(: For the weapon switch and zoom you could have a look at the FPS Game that Epic has in the Market