1. What is hash
A mathematical calculation used to create a new block for the blockchain. Specifically bitcoin uses the SHA256 hash. Details about this calculation can be found here:
http://en.wikipedia.org/wiki/SHA256hashrate?
The speed at which a piece of computer hardware can perform the hash calculation. Typically measured in terms of number of completed hash calculations per second.
2. How does "double spending" happen?
It depends on the definition of "spending". In bitcoin, true double-spending is not possible. That is the crypto-currency problem that bitcoin solved. In general, when people talk about double-spending with bitcoin they are talking about a two separate transactions that are broadcast onto the bitcoin network each spending the exact same unspent output but with differing sets of new outputs. At most, only one of the two transactions will make it permanently into the blockchain. The other attempt will simply cease to exist.
3. How does the network "confirm" a transaction?
A miner somewhere solves a block that contains the transaction and then broadcasts that block to be added to the blockchain that every full node maintains a copy of.
4. How does blockchain.info get all of its information about transactions?
They run full nodes and scan all blocks and transactions received. They then make a permanent indexed database entry into their own database for each piece of information so they can quickly provide details on the website and through their API interface.
If I wanted to access those transactions could I (assuming I know how to program) write some code that would mimic blockchain?
Yes.
5. I've seen faucets that ask for an inputs.io email address. How can bitcoins be sent simply with the knowledge of an email address?
I don't know much about inputs.io I suppose they may perhaps store a user's email address and link it to the account that they maintain. Then when someone sends bitcoins to inputs.io and tells inputs.io to credit those bitcoins to the account that is associated with a particular email address, inputs.io can look up the email address in their database and credit the account appropriately.
Hope you can help
I tried.
Thanks
You're Welcome.
