re: The CEV will be able to take astronauts to any altitude
The CEV should have other capabilities besides merely delivering astronauts to the moon. In theory the CEV could be used to service or assemble satellites at any altitude, e.g. big telecommunications satellites in geosynchronous orbits, or even higher. The space shuttle could never achieve those altitudes. The CEV ought to have the capability to do something once it gets there. Assembly of a big manned Mars spacecraft is another future application for a CEV robotic arm, unless the ISS will be reconfigured and used as a mars spacecraft?