nissan micra 2005 1.2

hi i bought a nissan 05 plate 1.2 ltr from an auction. its done 70k miles and has only 3 stamps.

1) the engine judders while stationery .
2) hissing noise coming from the engine after u drive it for 20 mins.
3) new problem- 1st gear only goes upto like 5mph then starts judddering, 2nd gear upto 10mph then judders so on and 5th gear top speed was 45mph then it starts juddering....however after leaving the car for 2 hours and trying it agian after it worked fine apart from problems 1,2 still there.

any sort of help would be greatfull thanks
ali