It's no so much that the person is supposed to look "unintelligent," but more that the author is trying to capture a particular dialect of English, a particular colloquial way of speaking. If you visit certain parts of England, where Harry Potter takes place, you'll find people who speak like this. Have you seen any of the Harry Potter films? They would give you a better since of how this kind of speech actually sounds. I can't comment on the Russian translation, but it's probably rendered as grammatically correct because there's no way to translate this specific dialectical way of speaking into Russian. Hope that helps!

You can also say something like "shifted the blame." For example, "I lost the house key, but I shifted the blame to my brother."

People tend to use both. Honestly, it depends on how "close" you feel to the animal. When talking about their pets, people will often use personal pronouns such as "he" or "she," but "it" is also acceptable.

full day

Today I have a full day. I must go to work, and then I must quickly go fast to pay the eletric electric and water bills, otherwise or they will be turn turned off. After I will be succeed to pay have paid the bills I can need to go grocery shopping because I i finisched finished everything that I had into the fridge. After that I will be doing do the shopping I will call my girlfriend and i ask her if she wants dine with me. If she accepts, i I will go to home for to set up the dinner. I hope of succeed I will be able to do anything.

Notes: "my girl" While some people (at least in America) do refer to their girlfriend as their "girl," it's generally considered sexist (or at least old-fashioned) to say that now. "Girlfriend" is now the preferred, non-sexist term.