I've also heard about high Nyingma lamas, like Chatral Rinpoche and Patrul Rinpiche, being strong proponents of vegetarianisms. Do you know what their view are when it comes to meat at tsok?
You know, that's a good question. Chatral Rinpoche very well may hold a view identical to many Kagyu lamas that it's unnecessary even at tsok, and Patrul Rinpoche might have too, but I can't say for sure. The only hard and fast rule I know of regards not refusing any offerings received in the tsok. Aside from the meat, this generally is much less an issue than is guarding against attachment to the typically delicious things that make up the rest of the tsok lol.
For me it is not the death of animals that is the problem, but the intentional killing. The way I understand it is that the animals death is the result of their previous karma, but our killing is the cause of our future suffering. Everybody involved in the process of meat production, the farmer who raise the animal, the ones transporting the livestock to the slaughterhouse, the ones selling the meat, and the buyers, all share the same karma as the butcher. Maybe I'm mistaken in my shallow understanding of cause and effect.
Your understanding certainly doesn't sound shallow at all. I think the difference between normal consumption of meat and this purchase and consumption is twofold. First, when one goes to the store and sees these piles of the cut up carcasses of slaughtered animals, knowing they will keep coming in by the truckload even though one personally abstains from meat, it's really very sad. It's as though there's nothing one can do. One might wish to take an inevitable cycle of suffering and transform at least a small part of it to bring about some good for some of the poor creatures. It is in this vein that one can purchase a small amount of meat, rather infrequently, so as not to really impact supply and demand, and purchase this meat not out of desire to enjoy it or for sustenance, but rather to mentally transform into a wisdom substance beyond the labels of purity and impurity, and offer and consume a bit of it as such, within the view of purity and equality, beyond subject and object (or with the aspiration toward that). So the intention is different.
The second reason I think it's different is also because all beings, including these animals that are now dead regardless of whether one abstains or not, are among the field of sentient beings one has vowed to stick by and lead to liberation once one has attained enlightenment. By using a small portion of their flesh, which would have either been consumed by someone else or have gone to waste, one is making a connection with that animal personally, making a strong auspicious link between it and one's bodhicitta aspiration, as well as with the blessings of the Three Roots. So I believe there is some benefit to the deceased animal(s) because of this and because of the compassion and blessings of the Three Roots. I personally choose to pray that the suffering they endured from the time they were born to the time they were slaughtered, as well as suffering in the bardo, will have been the cause of the exhaustion of the remainder of their karma, and that by virtue of making a connection with the Three Jewels and Three Roots by way of the most valuable thing they had to offer - their bodies - it may be a cause for their liberation and enlightenment.
I can certainly understand if you still feel differently, and would encourage you to speak with a prospective lama about this in private before making any commitments with him/her so you can be sure to form a commitment with a lama whose views are compatible with yours. Because they're out there. Regardless, once you've received empowerment and samaya, if you end up in a tsok you did not organize but are simply participating in, and it turns out there's meat present, you mustn't refuse it if it ends up on your plate, and can eat it sure of no fault since you only have the intention to make a connection and benefit the now deceased sentient being and had nothing to do with its inclusion in the tsok. At no point would you have rejoiced in the animal's death or agreed with it just by consuming whatever was given to you with a view of emptiness and equanimity. In terms of training in pure perception of the normally repulsive items that you might happen to receive during tsok (meat or otherwise... for instance I normally perceive mayonaise or things made with it pretty gross!), you also don't necessarily have to eat the whole portion of such items, just at least a small bit of them (though without rejecting the remaining portion) and while transforming your experience according to the instructions you will have received. Then, whatever leftovers you have you can respectfully offer outside. Hopefully, we'll one day be able to realize the actual primordial purity of all phenomena and then gross things at tsok (or elsewhere!) will be a delusion of the past!
Is this also the chronological order of the process? Do you receive the explanation only after the empowerment and reading transmission?
Generally speaking, yes, although many lamas are nowadays explaining a great deal that in ancient times would have been reserved exclusively for after empowerment had been received and vows taken. I imagine this is due to the frequency with which they've encountered very critically-thinking Westerners who like to be well informed before making an important decision and commitment. Originally, those in the position to enter into empowerment would generally have already been through a good amount of exoteric Dharma practice and would have become sure of their refuge, their bodhicitta determination, and of the authenticity of the vajra master they were going to receive empowerment from so that they would be willing to enter into empowerment and accept whatever commitments might come with it, knowing they'd be in line with bodhicitta. Nowadays, that's obviously a rarity.
Anyhow, the very best wishes to you on your path. May you be able to practice this precious vehicle in a way that is in accordance with your very kind conscience.