In regards to the first question, the only pulley providing a mechanical advantage is the moveable pulley, the other two (non moving) are only redirecting the direction of your force so they provide no MA.
The second question I'm 99% sure is a typo and should be 12" in the question not 10".
The third question, I'm not sure how I would set it up with a formula as it just seems intuitive to me. Every action has an equal and opposite reaction, if something with a mass of 150 lbs moves 10 feet, something 4x its mass has to move 1/4th of the distance. The way they have it set up is correct I just think its easier to think about the questions intuitively. The mechanical questions on the ASTB were roughly the same difficulty as those so I wouldn't stress about knowing formulas etc....
If there are problems you intuitively know the answer to you will be able to do the same thing on the ASTB....I was worried about formulas and ended up getting a 60 on the OAR which I was told is around 80th percentile. Also remember you have answer options and can work backwards which helps if you think about problems in more of an intuitive way isntead of formulas.
Hope this helped!