About American accent and pronunciation

I''m new here in this forum and I''m here just for one purpose: to learn English.

I wanna ask you the English-language wizards a couple of questions about American accent and pronunciation.

Most of the times I hear Americans pronounce T like D in. However, sometimes they make it exactly T as British do. So what is the rule for this?

Next I wanna ask about joing words. Sometimes I hear them join words, especially words that end in R with the word that follows. For example, I saw more in Hanoi than in Hai Phong. In this sentence, R that closes that word MORE is joined with I in the word IN. And that''s the general rule, isn''t it? In some cases, however, they do not join, or in other words they do not pronounce R. Why so?

Thanks

và theo nội quy của TTVN, bạn có thể bị khoá do nick quá dài. bạn có thể bị treo bởi bất kỳ mod nào (tớ quên mất giờ treo nên để dành cho mod khác ) Just kidding, yêu cầu bạn dùng username khác.
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Các bài viết của chủ đề này đã được Brit chuyển về đây: [topic]228722[/topic], xin phép khoá chủ đề.

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