Swapping hv battery electronics with new Toyota battery

It's been a successful first day on the DIY for swapping out the old hv battery.

So far I've gutted out the back and removed the old hv battery safely. I've had the help of a few members here so thank you!

I have a few questions on swapping over the electronic unit to the new battery. It's a bit frightening touching anything since it's a battery.

(1) Do I need to take off the metal casing to remove the existing wires on the electronics? (picture)

(2) How do I safely remove these wires? (picture1 picture2)

(3) How do I safely attach these wires to the new hv battery? (picture)

It's my first time working on a battery and I'm a bit nervous about hurting myself.