Здравствуйте, помогите правильно и красиво перевести письмо на английский язык

"Я против" надо сделать чуть мягче, но если вы хотите звучать категорично, то употребите I am agsinst this project.

I don't think I wuold support this project., because animals will be deprived of their natural habitat. It will result in their unnatural behaviour, because animals may feel uncomfortable in the new environment they are supposed//they are going/ to be kept in. The city is likely to have more unpleasant odors peculiar to animals.
Of course, this project has the upside: people and animals will get to know one another better. But unfortunstely that's the only advantage.
(Sir неудачное обращение для письма, поскольку является формой обращения к незнакомому лицу. Вы пишете письмо незнакомцу и интересуетесь его мнением? Вряд ли. Поэтому берите форму Mr. и придумайте фамилию.)
Mr. Green, I'd like to know your opinion on my letter. Please, let me know it/your latest news. (под "происходящим" что имеется в виду?)
Sincerely yours,
Catherine

Комплиментарная концовка, после которой запятая, а имя с новой строчки и без точки после него.

I'm against this project, because the animals will cease to live in their natural habitat. They will not behave naturally, they will not feel comfortable in the new environment, in which they are planned to be kept. Most likely that the number of unpleasant smells that are peculiar of animals will increase in the city.
Of course, it has its advantages, as people and animals would get to know each other better, but unfortunately it's the only advantage.
I would like to know what you think about my letter? Please, let me know what is going on.
Yours faithfully,
Ekaterina.

I am really against this project as animals will cease to live in their natural habitat. Their behaviour will seem unnatural, and they will not feel comfortable in their new habitat which they are planned to be transferred to. Most likely, city will feel more obnoxious odor that will be produced by animals. Of course there are some advantages. People would know animals better and animals would get closer to people. Though unfortunately these are the only two advantages.
Sir, could you please tell me what you think about this letter? Please let me know (или please let me know about the latest news)
Sincerely yours, Catherine.

I'm against this project, because the animals will cease to live in their habitat. They will not behave naturally, they aren't comfortable in the new environment which they plan to transfer .Most likely in the city, to increase the number of odors that will possess the animals.
Of course, this has its advantages, people would know closer animals, animals and people, but unfortunately it's the only plus.
I would like to know what you, sir, think about my letter? Let me know about what is happening.
Sincerely yours, Ekaterina .