No, it cannot maintain the metal touch switch, you need to use the switch which is included. since the metal touch switch is 120V, it cannot connect with light directly. The light is low voltage.
No, it is compatible with the 3LT Metal puck kit WH (SKU 1000028892).
No, it does not come with a dimmer.
I had the same question and the sales associate at my store opened the package and we measured it to be 3ft.
You could use an extension cord.