1) China has one prototype J-20.
2) What sort of engines does it have? This should be a concern over what powers this aircraft knowing how much difficulty Chian has had with the ws-10.
3) Weapons load is unknown as are electronics.
4) Is the aircraft in full production yet?
5) When shall the aircraft go into service?
From some of the photos leaked out in the past few weeks. We should be able to answer the first two questions.
1) CAC has at least two prototype J-20s. Although they all have 2001 number on them, there're certainly two types of engines used on those two prototypes.
2) This continues to the second question. From first few photos released we can definitely say one aircraft is fitted with two AL-31 series engines. However, the engines on other prototype is not that clear, at the moment. Well, the shape seems to be WS-10 series engines. But the colour and some details are slightly different from normal WS-10s we saw on J-10s and J11-Bs.
3) I personally don't think anyone here can even claim the real weapons load of J-10A/S/B, yet...
4) I don't think anybody thinks it's in any kind of production, at the moment.
5) Nobody can say exactly when (not even top PLAAF and CAC officials). But from what we know about the whole development of J-10 and J-11B, J-20 could be in service sometime around as early as 2018 or as late as 2022. But today's CAC isn't 90s' CAC. So this kind of prediction won't be anywhere as accurate as people think, anyway.