Hello Rabbi,
There are two things that bother me.
I’ll just preface by saying that it’s quite possible I’m not quoting exactly what is written there word for word.
1. It says in your name that not everything written in the Torah was given at Sinai, and that it is not entirely clear to us exactly what was given at Sinai.
2. Regarding animals, that you advocate vegetarianism and veganism because of the cruel treatment toward animals.
Thank you.

Hello Y.,
1. That is indeed correct. Assuming that everything was transmitted at Sinai exactly as it is raises some serious difficulties. Therefore several medieval authorities (Rishonim) already wrote that there were later additions. By the way, I am not saying that there definitely are such additions, only that I have no problem with the conclusion that there are. On the face of it, that seems reasonable, and I do not see any fundamental problem with it.
2. Now here you really surprised me. This is the “heresy” you found in my words? What problem do you find with this logical and moral claim? Industrial raising and slaughter of animals involve insane cruelty toward them (you can search online and you’ll find plenty. I only warn you that it is hard to watch). Therefore, morally, it is proper not to consume products from that industry, and there are even halakhic / of Jewish law aspects to this.
I’m attaching for you an essay that I disagree with on quite a number of points (mainly that it tries to force everything into Jewish law), but you can get an impression from it:
https://drive.google.com/open?id=157OabU7MxHteVBy6OOq74JfcWqDPvapb