It would be "don't gang up on me." The phrase "don't be a group of curs" is technically correct but sounds funny, because the word "cur" is very outdated.

It should be either "Am I making myself understood?" or "Have I made myself understood?" However, "Do you understand me?" sounds a bit more natural to me.

It depends on the context. "First" just means that the event happened before the other ones. "At first" means that the event happened first, but the result changed. For example, "At first I bought a new car for my trip, but then a friend of mine bought me a plane ticket, so I flew instead."

It is better to say "Please provide your name and address so that we can send you our samples." "Could you please" sounds less polite, more like a demand. "Recipient" sounds unnatural in this context. If "address" is already mentioned, the idea of "mailing" is implied, so "send" sounds better to me, but "send" could be replaced with "mail" without changing much.

The first is correct. I might say that in the right context. but a more colloquial way to say it is "Us two can't do it either." You can also say "Neither of us can do it" if the "either" isn't that important. The second should be "The slower you go, the faster time moves."

Without further context, there are two possible interpretations. Neither of these changes the word order; that is correct in either case. The first option is that some evidence is being used as news accounts. This seems strange to me, because news accounts are not used to support academic conclusions. However, they can influence public relations, so perhaps this is the meaning. I believe that the second interpretation is more likely, but this phrasing is complex and it took me a minute to understand it. The word "as" in this context means "like." The complaint is that the person is using news accounts, and other similarly dubious sources, as if they are evidence. The "as" shows that not only news accounts, but also other things, are part of the supposed evidence.

"On our side" is the expression. "In our side" might seem like it makes more sense, but it is incorrect. "In our side" actually sounds negative to me, as it reminds me of the expression "a thorn in our side," meaning "a long-standing problem or inconvenience."

Both "in" and "at" are acceptable here, but "at" is more common. However, "any of the kids" sounds strange. It should simply be "I just want him to fit in with the kids at his new school."