I'm no expert in this but I did a lot of research when building my electric go kart so I know a few things. Looking at your wish list, I can see you want to build a pretty powerful go kart. The reverse switch you have there isn't very good. I already went through 3 of them so I recommend getting this one. For the charger port you will need something like this and also a charging cable but double check if that charger port fits since I'm not sure what controller you are using. The batteries you are using will work fine but they are lead acid so they won't last long compared to lithium-ion batteries which last longer but are more expensive. I will list all the connections below. There are some that are required to run the go kart and the others are optional.
(Required)
Power (+/-): Connects to batteries
Motor Phase Wire: Connect to motor
Hall: Connects to foot throttle
Power Lock: Connects to ignition switch
Charger Port: Connects to charging port cable
(Optional)
Indicator Light: Shows motor controller status
Brake Light: Light turns on when braking
Low-level Brake: When braking, motor slows down automatically
Throttle: Connects to hand throttle
Reverse: Connects to hand throttle
3 Speed: Connects to Hand throttle
Here is a diagram in how to connect the batteries:
Something else I wanted to point out is that the motor wires will not directly go into your controller unless you don't want reverse. You will need to extend the motor wires to the front of your kart into the reverse switch (or wherever you decide to install it) and then wire it as shown in this diagram. Then run the wires from your reverse switch to the motor controller.
Reverse Switch- I'm planning on purchasing this for my go kart but I haven't tested it yet. I've heard it works fine so you can add this to your wishlist instead of the other one.
https://www.amazon.com/gp/product/B089DXS8HQ/ref=ox_sc_saved_title_6?smid=A2RVY1EQYPYVQD&psc=1
Charger Port: Double check if it fits with your motor controller
Charging Cable:
There are also kits you can buy online that come with everything you will need if you want to check them out:
https://cart.electricscooterparts.com/store/Search.aspx?SearchTerms=kart+kit