This website describes the mission in some detail, but it doesn't state who it was written by, or what its sources are, so consider this paragraph unconfirmed data. The launch mass of Chang'E 3 is 3700-3800kg. After arriving in a 100-kilometer circular orbit, a 1200-kg Lunar Landing Vehicle will separate and transfer to a 100-by-15 kilometer orbit. It will descend under power of thrusters to an altitude of 100 meters, at which point it will hover and use autonomous hazard avoidance capability to move horizontally until it has found a smooth place to land. Then it will descend to 4 meters, cut the engines, and drop to the surface. Once on the Moon, it has an operational lifetime of 12 lunar days.

According to this news article from August 2012, Chang'E 3 will be powered by a plutonium-238 radioisotope thermoelectric generator (RTG) in addition to the solar panels visible on the models. I had not been aware that China could produce the plutonium isotope needed to power an RTG. The article gives the impression that the RTG is there primarily to keep the spacecraft alive during lunar night.

The mission of the lander/rover is to perform "territory surveys, living conditions assessment, and space observations," according to a Xinhua article quoting Ye Peijian, chief commander of Chang'E 3 at China Academy of Space Technology.

The rover will weigh 100 kilograms and is intended to last 3 months, which means it can survive at least 3 long, cold lunar nights. If I'm interpreting the article correctly, it will be equipped with some autonomous hazard avoidance and navigation capability but will also be directly controllable from Earth.

The English-language website I linked to before says that the rover has an expected range of 10 kilometers and carries a 20-kilogram science payload.

Ouyang Ziyuan made this a lengthy presentation to the China Academy of Science about China's plans in space, I think in June 2012. It's the same presentation in which the plans to explore Toutatis with Chang'E 2 were disclosed. At the 208-minute mark, he spends about 10 minutes on Chang'E 3. User "Galactic Penguin" at NASAspaceflight.com translated and posted a few key details about the spacecraft from this post about Ouyang's presentation on a Chinese spaceflight forum: