Vector Triple Product -- from Wolfram MathWorld (then you only have to calculate scalar products).
Q2 Get e = a - b and f = a - c. Now calculate e x f. Add d to the result.
You should know how to calculate a cross/vector product ....
Slightly off-topic but this thread is too good an opportunity to pass up:
Question: What do you get when you cross a mountain-climber with a mosquito?
Answer: Nothing - You can't cross a scaler with a vector.