Back in 2016 my dad was diagnosed with diffuse large b cell non-hodgkin lymphoma, 11 months later i was in a similar situation to you.. Told he was 24-72 hours left and asked to sign a DNR as he detireorated.
It is hard to know what to say in terms of what to prepare for, but remember that the dying process is very natural. Don't overcrowd the room, make sure it is comfortable and ensure that friendly conversation is going on around him even if you think he can't hear, he probably can and this will bring great comfort.
In my dads case at least he was visibly in distress trying to fight the dying process away, this was exceptionally traumatic for us to witness, flailing arms etc. Eventually once the nurses have attached the syringe driver and the morphine is flowing this will ease up, the sooner you can get the staff administering the maximum amount of medicine to ensure comfort the better, luckily my mother (his ex wife) was a paliative care nurse for many years and helped us communicate with the nurses to ensure he had the highest dose possible.
In my fathers case his hands became very hot towards the end, his skin started to discolour as blood started to gather in the extremities, this as far as i know isn't perticuarly normal but it was a side effect of the sepsis caused by the cancer. The usual process has the extremities going pale and losing blood, thus going cold. The blood will move towards the chest and vital organs similarly to hyperthermia, the telltale sign for knowing that the time is near is when the nose becomes cold.
The moment of death can vary, don't expect a quiet and easy end. Often the diaphram inverts as the heart stops and fluid is often brought up during the death rattle, this can make it seem like the person is choking, they aren't at this point they have passed, but it is a part of the natural process. The quiet easy death can still occur however.
Studies have shown that the brain can stay active for a number of minutes following death, try and remain calm and hold your fathers hand, tell him how much you love him and how you will make him more proud than he already is.
Visiting hours don't apply to you.
You may feel like a weight has been lifed or a sense of relief once he has passed, this is normal and do not feel guilty for it. Cancer isn't about the death, it robs you of a good nights sleep from diagnosis to either cure or loss...
I am sorry for being so honest with this, but i wanted to share my experience.
I wish you all the luck moving forwards and hope your dad has a peaceful passing.