That's a very good offer, a lot of busy people can be interested by your service.
I also recommend you to give a vouch to a trusted member, so that interested people can see what your work looks like.
Not at all. That's not a good idea at all.
Op is offering something which will do him some good by getting some money, but it is harming the some one's future. They will get their assignments done by paying some money but when in real exam, they will just fail.
Plus, if the institution comes to know of this, they may take disciplinary action against the student too.
In the past I have observed many people came with similar services but not seeing anyone sustaining. Probably parents and institutions might not prefer availing such services.