Hey, take it from a guy who has been doing this his whole life. I am naturally tall and thin, and my football and baseball coaches wanted me to put on muscle to have more power. It's hard to do, but with a good diet and workout routine I've gone from 6'1'' and 160lbs to 185lbs, while still staying under 10% bodyfat.
Okay, so first of all there is one type of whey protein. It is not "raw" or anything like that, it is just called whey protein. It is great for you, and if you plan to work out I highly recommend it.
If you want to buy a ready made weight gaining powder, those are good but they can be expensive. They are entirely not necessary though; I've never liked them.
If you want to gain weight through diet, these foods are the best way to do it
-whole grain breads and pastas
-kidney and black beans
-whole, uncut (old fashioned) oatmeal
When you are trying to gain weight, it's a simple calories in vs out calculation. If you take in more than you burn, you will have a calorie surplus and gain weight. Like another poster said, you should also stop at a fast food place 2-3 times a week and grab a few sandwiches off the dollar menu, sticking to burgers and chicken sandwiches (wraps or fish won't do much for you).
To gain that much weight though requires a solid lifting routine, otherwise you'll put on fat. Focus on compound exercises, with medium-heavy weight, and a moderate rep scheme. If you workout four times a week, try to keep it under an hour each time; if three times a week (this is what I do), keep it under 1.5 hours.
If you need suggestions on exercises, supplement recommedations, or anything else just post it here. I've been fighting my ultra fast metabolism for years in sports so I know quite a bit about this LOL.
And unfortunately, anytime you up your caloric intake you have a slight risk in getting some new acne. The effect is usually minimal, and it usually clears up once your body has become acclimated to your new routine.