1. 我今天跟你一起要去香港。--- a declarative sentence. 2. 今天我要跟你一起去香港。--- what am i gonna to do today??? go to hongkong with u! 3. 我要今天跟你一起去香港。--- when do i go to hongkong with u? it's today! not tomorrow!

1. 我今天跟你一起要去香港。 2. 今天我要跟你一起去香港。 3. 我要今天跟你一起去香港。 #1 & #2 has the same meaning but the emphasis is different. #1 emphasizes "me", 2. emphasizes "today". You are following someone to HK and both of you HAVE/MUST to go [because of some important thing to do]. Usually #2 is the preferable way of saying. #3 has a different meaning... It is the time that you must go with that person. Any other day won't do. If you change the word order into 今天我要跟你一起去香港 It can be translated as I MUST go with you to HK... It is not because of HK that you have to go but you go because of that person is going! "Today, I HAVE to go with you to HK" However, most important determiner is the context. It is just like using ""

The second answer is better. (今天) 我要跟你一起去香港。 “我要和你一起去香港” is an independent sentence. So put "time" in the sentence before will be better. You can be changed in any time.

2和3都可以。2更常见，3从语气上，更加强调“今天”。其实中文很多时候，顺序不是很重要。

там 要 без надобности 我 今天 跟 你 一起 去 香港。 = 今天 我 跟 你 一起 去 香港。