The description given in question 3 is clear as mud. However it does seem to say that there are 2 cylindrical helical gears meshing with their shafts skew. To solve this, you need to know that 2 helical gears with the same hand and 30 degree helix angle can mesh with their shafts at an angle of 60 degrees.
Once you know the helix angle, you can calculate the normal pitch which is different to pitch on a circle because it is the pitch on a 30 degree helix. The answer is d.
After all that, 4 is relatively easy - an 8" gear has 8/6 times as many teeth as a 6" gear if the pitch and helix angle are the same.