From what I gathered, there are many ways to request something of someone. For example, consider:
2. 伝えてくれれば助かります (This sounds like if you relay (the message), I will be saved, but my colleagues told me it's more like saying thanks, so its real translation is I will be thankful if you relay the message)
3. 伝えてくれれば感謝します (This sounds exactly like sentence 2, but I have never heard it before for some reason)
4. 伝えて欲しいなぁ (This sounds like I am forcing someone to do something)
5. 伝えてください (Translates to please relay the message, but sounds like I am forcing again, such that he doesn't have a choice)
So now the question is, under which circumstances should I say each sentence? I'm looking for a semi casual-ish style (to put it in a fashion sense, almost like a man wearing a polo shirt and jeans to work instead of a full body suit), and also one that doesn't give the impression that I am forcing someone to do something (like in sentence 4 and 5).