1)
Is this a realistic goal for China?-
Yes, and a very healthy one IMHO- I think that engaging in some space colonization is pretty healthy for thier culture and economy. I have a feeling the Chinese are holding to the political stereotype of looking at things in a large time frame.
The entire moon landing shoved our own tech forward with a vengence, and will probably have the same effect on thier culture and economy as it had on ours.
Also, there is alot of money in the space program in spin offs as it turns out. Like regular sattelite launches. Russia is the "bread and butter" favorite on this one right now.
Also, every country with a space program ought to be looking towards colonization of our nearest planets. Who knows what discoveries this will bring- and the society that doesn't strive to keep up in this area will probably see alot of it's influence fade away. I would bet money that this entire venture is in the hopes of starting a commercial space industry. I also think they DO have natural resources in mind as well- getting a colony on the moon of what is, in reality, a really big space station with a smaller gravity well than earth- a natural for a "shipping harbour" of you will

- China is feeling the pinch of future peak oil, scarcity of resources to get the stuff they need for thier huge new manufacturing economy base. What would happen to the stability of china if the main underpinnings of thier new economy, manufacturing, were to have to shut down for lack of resources to run them?
2. If this is a success, what are the implications for the world? (In particular, how will this effect the space programs of other nations, or international programs? And is lunar helium-3 really an important potential resource?)Like I said above- a nation that really falls behind in this, especially the western nations, will probably be in big trouble in a couple decades!
Who knows- Chinese physicists and engineers are no better or worse than the western nations and Russia - so perhaps the chinese are taking a big gamble to be the next Saudi Arabia?