Does changing one's intention from hastening (ta’ajjul) to not hastening in stoning the Jamarat affect the validity of the stoning or the Hajj, and is staying six hours at night in Mina sufficient for the Mabit (overnight stay)?

The criterion for achieving ta'ajjal (expedited departure) is departing from Mina before sunset on the second day. If the sun sets upon him before his departure, then, according to the majority of scholars, he has not achieved ta'ajjal. If the sun sets while he is still in Mina, he must remain until he stones on the third day. A mere intention to depart early is not sufficient. Furthermore, retracting the intention for ta'ajjal does not invalidate the stoning or the Hajj. As for spending the night in Mina, if you stay there for more than half the night, it is considered sufficient.