In response to the question - how and in what way in Chod is the body offered to the demons? And how do they feast upon them?
There is a limit to what I can say in reponse to this, as the sadhana itself is covered by samaya, so you would need the empowerments to practice Chod, and then you would receive the instructions which would clear up your questions. However, I can talk in very general terms, and hope that that will suffice.
Well, in Chod practice the body (and other dharmas) are offered in terms of visualisation, or imagination, if you prefer that term. By which I mean that in the course of the sadhana one visualises giving away your own body in order to satisfy all the beings that you are karmically connected with. In the process, one works with one's attachment to your body, which is a very deep seated attachment. And, one works with one's attachment to a sense of self, which is even more fundamental. In practicing these acts of compassion and generosity (mentally giving one's body to be devoured by those who wish to devour it), one develops on the path. Of course, one also maintains a view of emptiness throughout.
What is actually meant here by demon? Is it some kind of a beast? Or an evil spirit?
In the context of Chod practice, as I mentioned in my original post, demons are designated in two terms, both as seemingly 'externally' existing beings, and in terms of seemingly 'internal' mental states. In both cases the demons are to be pacified. Chod is used to exorcise places and people, to clear away harmful spirits and demons, and it is also used to develop realisation of the nature of mind.
Do evil spirits exist?
Forgive me for not answering directly, but could I ask you a question in turn? Do you exist? Perhaps you could share your response to this, as I believe it to be a useful basis from which to answer your question.
Of course there are people who are constantly wicked? But from Buddhist view how do they function?
Actions breed consequences. When a being commits an unskilful act, then the tendency to commit further unskilful acts becomes that little bit stronger. We are creatures of habit, as they say. It's rather like our actions cut a groove in a turning piece on a potters wheel ... each time the unskilful action is made, the groove is cut into the piece, making us more likely to follow that groove the next time a similar circumstance arises. Speaking relatively, the Dharma path consists of replacing our constantly unskilful actions or habits with skilful or positive habits and actions. Each time we do that we set in motion a chain of events that makes it that little bit easier to do further skilful actions. Until the point where we break through the chain of habits and realising the nature of mind, we no longer act from habit, nor create future habits (karma).
Is it true that your sister-in-law vomitted razor blades? I cannot believe it because how is such a thing possible?
Well, I wasn't personally there, but have no reason to doubt what my wife saw. When living in Malaysia, I had friends who regularly saw spirits and ghosts, as common-place as people where I live now see dogs or cats. People becoming possessed, either intentionally, or not was common-place too. My own experience is that the east is quite different from the west in a sense, that people view the world differently, and experience it differently. One's views and experience of the world is a product of ones karma and past experience. Coming to live in the UK now, I certainly experience the world here as being what used to be called 'Godless', a very much less animate and vibrant world, in terms of the inhabitance of the same space by beings of different types.
If you feel so inclined, I'd be very interested to hear your response to my question 'do you exist', and hope this will prove a useful basis for intestigating your experience futher. Asking questions about what exists is one of the key means to develop ones view and provide the basis for direct experience of the nature of mind.
very best wishes to you ....