They have tried a new engine yesterday which is thought to be WS-15 with Thrust vectoring nozzles. TVC nozzles do not have to be loose like you see in Flanker family it can be straight and upright like the F-22 and EJ-200 which looks more like a F-100 but actually its a TV Nozzle.
Canards are not a big issue , they have done their homework before putting them on , T-50 also have small Canards and btw of that is the case then F-35B isn't very stealth because of its opening jet doors for VTOL.
Remember this is just a freaking prototype the real design would be much much different , fine and neat as during evaluation different flaws will come to light and later they would be fixed to bring out a production model which won't be any less than the F-22.
Thanks.