iserith
Magic Wordsmith
No - moving is given as an example of a readied action in the phb and dash gives extra movement equal to your speed, it does not ×2 your speed. This helps avoid stacking issues eg if someone dashes and also has a bonus action that can be used to dash - with 30' movement that makes 30+30+30 = 90' total movement.
Edit: If the 'problem' is that a 30' speed character can't move 60' with a Readied action, well yes that's true and intentional. You can move 30' on your turn, Ready, then move 30' again as a Readied action though.
Yes, you can ready a move as I said upthread I believe. But readying a Dash does nothing since it does not allow you to move.