(aside form Q2) all of these questions look very easy. If you are given the units for each given value, and if you know the units you need for your answer, then for the most part you just need to manipulate your given values until you end up with the required units. i.e. if given 10km, 3m/s, and told to find answer in s with 3SD, then 10km = 10000m, (10000m)/(3m/s) = 3333.33...s = 3330s
Also this post should be in the pre-University section. Checking out the other questions on this forum would make it apparent that "hard" is relative.