#3 is more colloquial and is what we really speak.
But there is a slight difference between 您使用微信吗？/您用微信吗？ and 你有微信嗎？
1. 你有微信嗎？ implies that if you do use WeChat, I would like to add you. 您使用微信吗？/您用微信吗？ is less implying.
2. Under this situation 您使用微信吗？/您用微信吗？ is way more ideal.
The company Tencent does market research on the street for WeChat. Their staffs walk to the people and ask: 您使用微信吗？/您用微信吗？
'你有微信嗎' is often but not necessarily followed by a friend request. It can be followed by a notification that the discussion will then be held on WeChat, or in the context of a street survey, questions about the user's experience with WeChat, etc.