seraching for help

My Father was diagnosed with Linitis Plastica last June(2009) and was told his entire stomach was rigid and inoperable. He had been unwell for about 24mths prior to diagnosis. The Oncologist's assistant said that his prognosis was 2mths to 'who knows' as this was a rare cancer and they didn't know how it would play out. He was offered chemo as part of palliative care, my Father decided against it as he wanted to be 'well' for whatever time he had left.
We are caught up in the 'waiting for God' syndrome as a family and I am finding it very difficult to know what to do for the best.
My father has lost a lot of weight but still eats solid food, all manner of things my Mother tempts him with. What is this cottage cheese and flax seed diet?? He does however have considerable pain after eating anything.
He now stays in bed most of the time, doesn't get dressed and seems to shut himself away. I know he is now depressed but don't know how to get through to him.
He has intense fatigue, which is now getting muddled up with the depression I think. He does get up and come downstairs every few days, usually to watch a rugby match.
His mother had a similar cancer in the early '70's and had a terrible end and this is a real fear for him, he is constantly comparing his situation to that of his Mother's. She was heavily sedated for a few months before the end and he simply doesn't want to be like that so he is not willing to take any pain killers at the moment, save a couple of paracetamol sometimes. I have tried to say to Mum that he understands his own pain threshold but she is now getting to the end of her tether.
My parents are intensly private people about personal matters and it is very hard to get through. My Dad sat my sister and I down to tell us the news but doesn't seem to want to talk about it anymore. Mum says he won't say too much to her either. My dear Father is struggling on wanting to keep this all to himself so he doesn't break down or worry us all. That said we all tell each other we love each other and we kiss and cuddle our Dad often.
I have just run out of ideas. I don't know what to do.
I almost daren't ask but how does this particular cancer play out? What should we expect?