Translation:We have to leave a little earlier.
its a pretty flexible word. It's interpretation depends on context. It has other meanings too. eg 我要去中国 doesn't mean "I want to go to China" but rather "I'm going to China" and will be met with a reply enquiring on when you are going [ with the expectation that you're going in the near future].
I don't believe so. Please bear in mind that this is the beta version of an very rushed product. Flag away!
I put "We want to leave a little earlier." and was marked wrong for the 'want' instead of 'have'. I've reported this as it comes down to intonation in English and also Chinese.
If I emphasise "want" in the sentence then it does mean exactly the same as 要. In either language, if you mean it more strongly, then you emphasise even further with "have" or "must" and the Chinese equivalents of "需要" or "必须". (There are many options.)