What exactly happens after death? Is there a Barzaq where a window is seen through which either breeze from heaven or fire from Hell is felt? And if it is so, then doesn't a person already know that he'll be in Heaven or Hell before the Day of Judgement? So then what is actually judged on that Day?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

In relation to your question 'What happens after death?' and the life in Barzakh (life in the tomb after death), you can refer to Fataawa: 82911 and 83540. As regards why there is pleasure and torture of the grave, the answer is in Fatwa: 89086.

For your other inquiries, you have to know that Allaah cannot be questioned as to what He does. Both the pleasure and torture of the grave are confirmed by the Book of Allaah, the Sunnah of the Prophet and the consensus of the companions .

Concerning your question: 'Why people are judged on the Day of Judgement?' the answer is that it is Allaah who decreed the punishment of the grave and its pleasure for the people, and it is He who decreed resurrection for the people to be judged. Had Allaah wanted only to punish them or please them in the grave, He would have done so but He decreed their resurrection based on His full Wisdom and Command. So it is wrong to ask such a question. Allaah says (which means): {He cannot be questioned as to what He does, while they will be questioned.}[21:23]. This means that the creation cannot ask Him about what He pre-destined to happen to His creation while He asks His Creation about their deeds as they are His slaves. It is reported that Ibn 'Abbaas said: "When Allaah sent Moosaa (Moses) and spoke to him and revealed to him the Torah, Moosaa told his Lord: ''O Allaah you are 'Atheem (a great Lord), had You wished to be obeyed, You will be obeyed and had You wished not to be disobeyed, You will not be disobeyed, and You like to be obeyed, so how come that people disobey You, O! Lord." So, Allaah revealed to him (which means): {I cannot be questioned as to what I do, while they will be questioned.}.

Allaah knows best.