1) Is a written divorce correct or not? Also joining the relation after divorce is it allowed?
2) Or talak k bad Agar wapas rishta jorna ho to halala hota h.

1) Talaq has to be verbal pronounced in correct Arabic in the presence of 2 just witnesses. Any other method and it will not be Talaq.
2) Talaq ke baad waapis rishta nahi jorra jasakta jab ke 3 dafa Talaq hogayi ho