Orion is not a rocket and makes for a terrible moon base. Speaking of which: the entire NASA plan is idiotic and is a waste of money.
Here is what we should do:
1. Remotely (with orbiting craft) explore moon's surface for presence of water and minerals. (partially done).
2. Launch robotic exploration rovers (Curiosity on steroids) for detailed lunological survey. Produce them serially for lower per unit cost.
3. Construct pilot ISRU and automatic construction unmanned bases. Test processes and designs for optimal performance. Learn from mistakes.
4. Construct second generation ISRU and automatic construction bases that will accept a human crew.
5. Launch a shuttle with will be constantly circulating between LEO and moon orbit, transferring crew back and forth. Use chemical rocket for initial propulsion and hydrogen cell powered VASIMR for orbit maintenance.
6. After a few test orbits, use it to send the first crew to the moon base. Their role should be to construct (with automated help) future facilities that will supply water, hydrogen, and oxygen to feed further space exploration and supply fuel to LEO and GEO. As well as preparing quarters for future extended crews.
Just reaching stage 3 will be 5x more expensive than NASA current plans and a human won't step on the moon until well into 2030s. However, once we get there, we'll stay for good. Alternatively, we can conduct junior high school science fair experiments on ISS and then go to the moon to plant a few flags and play golf.