Of course yes, anyone can used bitcoin, even the student, vendor or ordinary people. Even the rich level of people allowed to used bitcoin. Because bitcoin is for anyone or for everyone.
Yes. Everyone is free to use it. No one can use it. I think those people who has lack of money is the most people who needed to use and learn how to use it. Bitcoin might help us very much. It can save them for not having a food to eat. They only need a cellphone for them to earn bitcoin and thats it.
You can understand and be able to use bitcoin. And if you can do that you're free to use bitcoin. There is not even a rule in it. So no one forbids you to use bitcoin for any particular thing. That's why bitcoin is called freedom currency