hya pal, normally most questions are answered in the nutrition section.
but first we need to know wat your goals are.
if your wanting to gain a lot of weight and bulk up on muscle and fat, and then cut to be ripped. to gain muscle, if your thin, youll need to bulk and gain weight to convert that into muscle. then you cut.
i dont know how much powder youll get for that money, but some of the best stuff can be found on ebay suppliment stores.
the protein powder your after is called whey.
the amount of times a day you will need to take it depends on how often you train. altho you do not only take it on the days you train. if you want to bulk however you will need to train more than 3-4 times a week. in which case you will be taking the powder twice a day inbetween meals.
if you buy a quality whey then there are no sideaffects. it is definatley 100% not steriods lmao! it is purely protein and acids, to help the recovery and growth of muscle tissue in a completely natural way. steriods which i would personally recommend never using, stimulate the muscle and give energy and they do have side affects.
a "better" suppliment (altho less affective) is creatine, you will find most people on here use it. i personally dont. it basically gives you more engery, it is also a natural chemical found in your muscles that give you energy. it wont make you stronger, it will just aid you to do another set.
if you stop having your whey shakes then your muscles wont shrink no. this question is also slightly confusing as if you wanted to stop taking it, i assume that you will have stopped working out, which again leads to my question of what are your aims?
and god knows what people are on about when they say your muscle shrinks wen you stop having them. muscle is muscle. it wont dissapear, unless you are working out and NOT taking the whey. when you work out, you burn the muscle fibres away and then to compensate your body rebuilds them and then some more in preperation of you having to lift them weights again.
lots of people have just the white. but for now have all of it lol. and if you eat them raw, you only get 50% of the protein youd get if you cooked them.
http://www.discussbodybuilding.com/Master_Grocery_List_Stick__the_top/m_120408/tm.htm this is a shopping list of all the best foods. to bulk youll need six meals a day, to aid you metabolism.
they need to be BALANCED meals. lots of complex carbs (50%) proteins (25%) fat(25%)
no processed foods! no artificial sugars!
as far as workout programes go, theres lots on here.
http://www.discussbodybuilding.com/The_Basics/m_2191/tm.htm any Q's feel free to ask.