Since some of the blockrewards for each block is split between the miners SmartRewards, SmartHive Development and the others you mention.
The reason it comes in at a steady flow of transaction is because this coin isn't premined and they've allocated a % cut off each block being mined into being allocated to the different projects.
Yeah that is a huge advantage and creates a really wide distribution.
Yes, all who help building SmartCash in some form or another will earn SmartCash and can empower themselves with the passive income features that incentivize holding.