1. By executing a registered Release Deed relinquishing his share in the property in favour of his son, the father can transfer his equal share in the property in favour of his son. After this exercise, the son becomes the absolute owner of the property ( assuming that this son has no siblings ).
2. No, Son by just procuring Khatha in his name with consent of his father can't become absolute owner of the property.
3. Legally speaking the SPA may not be valid, as the son is not the absolute owner of the property.
4. (a). Executing sale deed by both father and son using a fresh POA.
(b). Relinquishment Deed to be executed by the father in favour of his son first and then using the current SPA to execute the sale deed in favour of the prospective buyer.