2) how decentralized are the full nodes in the network out there? - Fully decentralized anyone can run one.
3) who is going to update, maintaining and provide the necessary solutions for bugs, soft forks as this technology progresses through time and scale? - People who believe in the decentralization of money. Hence running a full node in your basement allows you the ability to contribute and validate the blockchain as it scales. Offsetting the comment in argument 1. big centralizing forces cant offset the myriads of little guys running full nodes in their basements.
Play with it. Playing with it will develop understanding of it 10X faster than reading about it.