How many hours should you plan to study per credit hour taken?
3 hours per 1 credit hour. This means that if you are taking 15 credit hours, you should be studying an additional 45 hours per week.
What is happening in a reaction when it reaches equilibrium? Is there still reaction occurring?
Products and reactants are being created at the same rate. Yes, this does not mean the reaction has stopped.
Which family of elements are not reactive and why?
The noble gases, because their valence electron shells are completely full and they don't require any more electrons to be stable.