Everyone of those SMT will give an airdrop to steem holders?
As far as I understand, is that those SMT will increase the demand for steem, making it a more valuable token. But I haven't read anything about airdrops, except the vice air drop that is in a few years.
Not necessarily. Only if the owners choose to.
However, if one is starting with the reward system, it makes sense to try and draw in some newer people, those who know how the system works, so that they can help to kickstart it.