"is what we take to be happiness also a source of suffering?
What we normally call happiness is also a source of suffering, because it involves attachment, illusion, conflict, etc.
is there a happiness without suffering?"
Perhaps one day. In the meantime, unnecessary suffering can be reduced to the point where we can genuinely report "I'm happy," and "Happiness is our nature," and "I live in a happy world."
"[Are we] the same consciousness when you were 4yo? the same consciousness as yesterday? if so, show me that consciousness of yesterday? what about when you sleep? what happened to that unchanging consciousness?"
It seems to me that we are the same consciousness as when we were 4yo. Experience changes, but the same perceiving consciousness seems to be there. My fundamental perceiving seems to be the same as when I was a teenager and a child. Only the content changed. In sleep, the perceiving potential goes into abeyance. As soon as perceptions become available (dreams or feeling the bed or whatever), the perceiving happens again. So I presume the consciousness was dormant in deep sleep.
"disease is not suffering. suffering is when you cry or even consider committing suicide because you have lost something"
I think the distinction between natural suffering and human-caused suffering is useful. I agree that attachment causes suffering. But attachment is caused by people telling us to be attached this and that and by them distracting us away from the innate happiness of being.
"ultimately, when you or your loved one's face inevitable death, there is the condition that can generate suffering. no one can help you reduce or be free from suffering here except your own intelligence & mind or even your own faith… another cannot help you"
You are talking within the context of a deluded world. Imagine being in an enlightened world. Death would be much easier then, for many reasons.
"when a dying person is afflicted by a dreaded painful debilitating disease, such as cancer, where they require morphine, is 'happiness' their nature?"
Yes. Normally, physical pain and death are brief and passing. So maybe it's better to expand the on the conditions for happiness:
Happiness is your nature and is realised in a good environment and in a good body.
But that should be redundant because having a good body and a good environment would be the norm if the world understood that happiness is our nature. It's when we think happiness is elsewhere or elsetime that we create suffering for ourselves and others, and worsen natural suffering.
"what you are calling 'happiness' may not be the same as 'peace'… peace via acceptance may occur when dying from painful cancer but happiness, as a feeling, may not occur"
I reckon peace is the absence of excessive disturbance and excessive restriction. Dying from painful cancer is not peace or happiness. I don't have the goal of having happiness or peace in all circumstances. I don't think reliable peace is worthwhile except when you are in a hopeless situation. If happiness is innate, and if your potentials want to manifest (they inevitably do), then why seek peace in all circumstances? I think we seek peace as a remedy to a deluded world that makes life and death unnecessarily difficult. Better to end the world's delusions than to seek immunity from it. Of course, I might be wrong. Perhaps there's no hope for the world and it is better to seek immunity from it. I suppose we'll see in time.
In the past, life sucked, but now we seem to have to possibility of creating a great human world. We might be in the process of that already.