Some general questions about blockchain consistency I basically understand the principles of a blockchain, nodes and miners. I also basically understand how transactions are hashed/calculated to be added to the chain but i doesnt understand the dezentralized part. 


For example bitcoin has a huge amount of nodes so its impossible to
be connected to all nodes. Is there some kind of
connection broker, root node thats always online or broadcasting that holds a list of nodes?
If a transaction is sucessfully hashed and published, how does it
reach all nodes so that nobody will work on an already added
transaction because he think its not finished yet? Ii think in some businesses its like on the wall street to fight about milliseconds.
For example bitcoin has a huge amount of nodes so its impossible to be connected to all nodes. Is there some kind of connection broker, root node thats always online or broadcasting that holds a list of nodes?


No, there is no hierarchy to the nodes. There is no reason to be connected to all nodes, messages are flooded to the network by peers.

There is a list of DNS seeds that will help a new node find peers to download the blockchain from when they don’t know any peers to connect to, read more here.


  If a transaction is sucessfully hashed and published, how does it reach all nodes so that nobody will work on an already added transaction because he think its not finished yet? Ii think in some businesses its like on the wall street to fight about milliseconds.


The FIBRE network allows miners to have exceptional connectivity, we can see the success of this in the low orphan block rate on the network.