Laws pertaining to the Slaughterer

Q: As we are aware, Brazil exports meat and meat products worldwide. Even within the Arab countries, these products are exported and, according to my information, they are halaal certified. As a result, many Muslims consume these products. 

However, I have noticed that our Ulama forbid consuming them. I have some questions regarding this: 

1. What is the position of our Ulama on Brazilian chicken, regardless of the brand? 

2. Are there certain brands that are genuinely halaal? 

3. On what basis is meat exported to Muslim countries and certified as halaal? 

4. Why do our Ulama and the Arab Ulama differ on this matter?

Q: Some of my family recite takbeer e tashreeq when slaughtering an animal rather than Bismillah Allahu Akbar which I know is sunnat. 

Will the meat be halaal with just any of Allah's names? I tried to correct it but they don't seem to be implementing.

Q: Is the slaughter by the Ahlul Kitaab halaal? Some said to me that Prophet Muhammad (sallallahu alaihi wasallam) used to eat the zabiha of the Yahood?

Q: Can a non-Muslim helper hold the animal whilst reading and making zabah of the animal for qurbani?

Q: Will a person be sinful if they cut their hair or nails during the first 10 days of Zul Hijjah if they are making qurbaani?

Q: Can a woman who is in her Haidh slaughter her own animal?

Q: In a family of 8, I am the only Muslim. I want to perform aqeeqah and I cannot slaughter. Can a non-Muslim slaughter for me?

Q: I live in Denmark and it is very difficult to find halal food here. My question is that can we eat the food of Ahle kitaab, like chicken, goat, etc. which is actually halal in Islam but Christians have cut them?

The question is that, is fish halal in all contexts?

Q: If a Shafee slaughters a sheep, intentionally leaving out the name of Allah on it, is it permissible for a hanafi to eat this meat?

Q: I slaughtered a few chickens recently for personal use. I have three questions:

1. On one chicken I noticed after cleaning that the main vein in the neck was not cut, is it halal?

2. I am uncertain if I read Bismillah on one. Is it halal?

3. If any are not Halal, what must be done with them?