The question says that it starts in 3 years time, which is time 3. It also says it lasts for 5 years, so it is received at times 3, 4, 5, 7, and 7 So time 3 – 7.
For question 2, whichever of the two gives the highest present value would be the one to choose.
(If you need help with the discounting then you need to watch the free lecture on investment appraisal (or the free Paper F2 lectures on discounting))