How totally totally devastating for you - my heart goes out to you so much. To lose a child must be the worst thing in the world - however in regards to your questions regarding a hospice, may I suggest that you do strongly consider this option.
Both of my parents were admitted to hospice in their final weeks of life, and my Father was so happy to be in a place were pain relief was administered professionally, without worry and without any stress on myself or my mother. He had previously been cared by myself and husband at our home, and although thankful for this, he was also grateful to be in the hospice, where he knew he was "safe" with all necessities at hand. I was able to take a bed into his room, and slept by his side every single night from admittance right up until his last moments. We too felt the pressure lifted by having Dad at the hospice, and My Mum was happpy to go when her time came, as she too knew of the care she would be given.
It is a personal choice though, and if your Son wants to stay at home and his family can care for him at home, then this is what you must aim to do, but please ensure you have the on-call care of the hospice at all times.
Wishing you all peace in at this trying time. I pray your son is kept free from pain, wherever he may be, and that you are all able to spend some quality time together at this stage of his illness.