I was also once a new player, and in some ways, I still am. When I was in your position I waited quite some time before buying new aircraft. I do not know what your Bank balance is so it is hard to recommend a good aircraft.
Should purchase a Super 748. They cost around 10,000,000 but seat 58 and have good range. I would start small and then go big, so right now the Super 748 would be good.
If you cant afford that, you should get a Shorts 300- 200. They cost 4,000,000 and seat 30. They are ideal for CAN - Shanghai or CAN- Beijing flights.
As for the focus cities, I would NOT recommend Kunming, Changsha, or Chongqing. I would go for more populous cities and cities out of China since you have enough flights inside. Try Ho Chi Minh City or Bangkok for a base. Also, fly to Hongkong and Taipei since they are big cities and there is lots of demand there.
Hope this advice works.
Pacific Traveler Airlines- Fly the Pacific Way