Validators receive rewards for participating in consensus and finalizing blocks. There is no precise per-block reward. Rewards are split proportionally among stakes within an era. If a validator is offline or cannot vote on many blocks, the rewards earned are also reduced. Delegators can only receive a proportional amount of the validator's rewards minus the validator's delegation rate. Rewards are distributed at the end of each era.
The root hash, or Merkle Root, is a representation of all the data in a given hash tree. Refer to Merkle tree if you wish to learn more.
A programming language similar to C++, designed for performance and safety, especially safe concurrency.