I can only speak to my experience arriving in Hanoi, but the e-visa fee was only the agents fee and you have to actually pay for the visa when you arrive. The exact amount depends on which visa you selected. (I had selected a 90 day multi entry visa, and the cost was $50 USD)
They asked for no ongoing travel or accommodation information. It was a bunch of 18 year old girls wearing military uniforms from 1975.