If someone is going to be late, I would prefer to receive a phone call as sometimes I don't hear/feel/receive text messages depending where I am or what I am doing. As for questions, I prefer to get them through email, as it is easier to keep a conversation going or include another party if necessary. Plus, you can also document the exchange in a way that is much more easy to access. That being said, I have contacted many people through text message if the conversation is not extremely urgent but needs a response in less than a few hours, does not require a long answer, or if I cannot stop what I am going long enough to make a phone call.