newguy,
I am kind of new at this thing myself.Maybe one of the other fine people here will give you a more complete answer,but i'll try my best.
1-Denominations are 1 cent,10 cent,25 cent,1 dollar and 2 dollars ( the 2 doolar coin is bimetallic).We call it a twoonie.(enter the word twoonie into Google pictures and you'll see it).These are obviously circulation.
2-Fake coins ?...never heard of such thing here,even though I am sure they exist,but not for the stuff I collect.I buy my coins sometimes directly from the
Royal Canadian Mint (
http://www.rcmint.ca),sometimes from
ebay other times from dealers.
The
Royal Canadian Mint deals only with this year issues,not the past years ( for that you'll have to go to on-line dealers).Buying from the Mint is a game,like anything else on this hobby.The particular coin might raise in value over time,or you might find out that if you wait a few years,you might find it cheaper on the secondary market.I don't think that I'm the right person to instruct you how to do your purchases.Personally I buy only coins I like,if they are limited edition is better,but I never bought a coin ( so far),just because it might raise in value.If it's butt ugly but people like it,then you'll have to search for answers to someone else who buys them as an investor more than collector.
3-I guess it's pretty sure to say that as far as the "most sought after" coins I've seen so far,it seems that our decimal coins ( cents and dollars) who are old.Older than 1950 or so.
The first Canadian 1 cent coin was issued in 1858 and the first dollar in 1935 ( according to a book I have).
One way to find out about Canadian coins is to buy a catalogue ( they are not expensive).You will see them listed there.
Another way to find out about recent collector coins/sets made either of normal metal or silver/gold is to check out the above link for the
Royal Canadian Mint.You can buy them directly from them,they have prices in US dollars.They also have information about mintage figures,dimensions and such for each coin/set.
The best way is to read a lot by yourself,sorry

,and when you know a little bit more about what you are after,ask questions here again.
I am sure that everyone here we'll try to help you.