Unity 2D game kit, implementing certain functions (dash, double jump), issues

Hello, I have been using this kit:

And it’s a fantastic base to build upon. However, I wanted to implement mechanics and things of my own. Currently, there are four things that I want to implement: Dash, Double Jump, Grabbing Ledges and Dialogues between characters. However, I have got problems making them work.

a) Dash:

I used this tutorial as I tried to make the character dash. I tried making a separate script for dash, but all it did was teleport the character back and forth and not move them. I used this as a base:

b) Double Jump:

I am not sure, how to implement this, with the current way the demo is set up. I tried to use this as a base, but it didn’t work:

c) Grabbing ledges/walls + Dialogues - I have yet to tackle these, as I want to make the first two work correctly.

The question is, what am I supposed to do to make it work with the 2D kit.

did u make it?