Beginner's Explanation I'm interested in learning more about how bitcoin, mining, and blockchain technology work. I'm a student and don't have a strong background in computing, and I'm looking for a layman's explanation of a few basic, yet critical questions surrounding the currency and the technology behind it. I plan on sharing the results with other interested students who want to understand more about this important concept. 


Miners receive 25 Bitcoins every time they create a hash (is this accurate?)- where do the coins they receive come from - are they fabricated or do they already exist somewhere? What I'm trying to understand is how the supply of currency changes - are there a fixed number of Bitcoins in existence, or is currency simply "created" whenever a miner updates the blockchain? As time goes on, will the money supply expand at some rate roughly equal to the growth in transactions - is this kind of like how the supply of fiat money in most economies has grown over time?
Is there a single blockchain for Bitcoin, which contains a record of all the transactions made since the first transaction? If so, does that mean that the chain will just keep getting longer and longer as more transactions are recorded? If Bitcoin increases in usage and popularity, won't the blockchain continue to grow (maybe exponentially) and will that add to the complexity of the miner's task?
This may be too complex to explain to an average person like me, but how do transactions actually get coded/added to the blockchain? I know that it requires brute force computing power and is based off of cryptography, but that's really the extent of my knowledge... If I wish to transfer 100 coins to my friend, that simple transaction must be captured somehow and translated into the chain - but how is this translation performed? Is there a constantly-changing key that has to be iteratively solved for by the miners? If a person were to "look" at the blockchain (I assume this is possible) - what would it look like, just a seemingly random collection of characters? 


I'll stop there, as I'm sure there aren't simple answers to these questions and I'm sure I've misused/misinterpreted terminology and how these things actually work. Many thanks to all who read my question, and special thanks to anyone who is willing to answer one or more of my questions. If there is a better forum for me to post beginner's questions like the ones above, I'd certainly like to know that as well.
I would recommend reading 'Mastering Bitcoin: Unlocking Digital Cryptocurrencies', by Andreas M. Antonopoulos.  This book answers all of the questions that you posed, and more, in a very understandable way.