confirmation before the funds become available for spending at BitSkins. (optional example Request bitcoin Deposit Rate. You will only get regular ones because its not possible to get StatTrak skins from drops. And most important of all they can be turned into real money if you want to cash out some of your inventory or decide to stop playing CS in the future. The most rare ones are worth more and the most common can be worth only a few cents. You should ask someone about it or use google to find out if the site you want to use is legit and safe to use.
Conversion rates are locked in when the Bitcoin network broadcasts your transaction. Playing CS GO, when you play on on official or community servers you will get random drops. I personally dont advice to open cases because you will most likely get cheap weapons and in general the method wont give you profit but if you like to gamble and have some spare bucks give it a go and see how it goes. The price of the key varies in-game and on market. The most common motive for price changes is when Steam starts game sales, like summer and xmas sales.