Since bitcoin isn't a company that might sue me for copyright or trademark, can I sell items with the bitcoin logo on them?  Same goes for all the others like Ethereum, litecoin, etc.  Does the fact that these are decentralized allow me to sell stuff using those names?

A hard fork always causes a chain to split into two.  Who actually creates the new chain and how?  Is this just the development community?  How can a minority of the devs create a new coin if consensus is required to change the protocol?

All these public companies run centralized businesses.  If blockchain technology is adopted, won't they all eventually go out of business to be replaced with decentralized systems that run on the blockchain?