Cymelo- you must understand that hebrew has different rules, and like every language, base on culture history and street. We don't have in hebrew, for example "past perfect" or "present perfect" and even our formal way to say something it's simple. As people wrote here you can always add "בבקשה" "תודה". We ask question as a sentence, that why when translate literally to english its sound like an order.. you can also ask אפשר.. which is "may I get". Good luck with your studies!
I have never heard הייתי רוצה used for a request — it sounds very strange. It's used to express something that you wish you had or you wish to know (I would like to have a big house and a million dollars, but I don't — ההיתי רוצה בית גדול ומליון דולר). To request something formally in writing you can say ברצוני לקבל (I would like to receive), ברצוני לדעת (I would like to know), etc. In spoken Hebrew the common polite form would be אפשר לקבל, אפשר לדעת, etc. It's not impolite to use אני רוצה especially if you add בבקשה. The less polite version (but often heard) is תן לי (Give me) — you can add בבקשה to that one to soften it a bit, too.