My main question here is, is this understanding correct or have I misunderstood something? If this question would be better for Reddit then I apologise in advance and I'll move to there. Thanks.
So technically I could download the bitcoin source code and run my own altcoin (let's call it pokercoin) on a network of 5 computers (for me and my 4 geeky friends who wanted to play poker without chips).
If I'm understanding correctly, we would each be running pokercoin source code/qt on our laptops and no other computers would be needed to keep the thing running (or maybe we would need to run something else to ensure the network works, because otherwise there is no other way of the network doing all the IP level stuff? Or do nodes do this and run something other than the bitcoin source code?).
When I make a payment, each of the other 4 computers receives a copy of that transaction, and they all add this to a block of 1 transaction which gets appended to our very short blockchain after 10 minutes (because hypothetically my computer is able to solve in 10 mins).
If 2 of us made a transaction, (the new block to be added has 2 transactions), but the other 3 computers wrote their own block which diverged in truth to my computer and my friend's computer, then this 51 percent attack would beat the previous block to be appended (or is it added only after ANOTHER block is added (because this is now the longest chain).
We all also get new pokercoin for being miners in our own system (or maybe it is only those running different code who get to be miners).
Finally, none of us actually argues over having any money, because we know that 'how much we own' is actually only made up of the network iterating over every transaction that happened in order to calculate our amounts (and this happens every time a new block is made).
We also don't argue over block sizes, because there are 5 of us.