1) Yes you do have to. You're the one trying to disprove generally accepted knowledge. In order to successfully do so, you have to show why their designs would be unable to make it outside of the atmosphere. You can't just claim something and support it with further speculation, as you just did.
I said nothing about making it out of the atmosphere, I said staying out of it, which would require a bunch of mass to eject.
2) Why would you have to constantly eject mass from the ship?
Otherwise, the ship won't go anywhere.
Thanks for the link, but you are the one who needs to read it.