Short answers:
Will features from busy migrate to Steemit?
I'm not a developer, but I hope so.
Is busy on the steemit blockchain?
Neither Busy nor Steemit are themselves on the blockchain, but are simply tools used to access the Steem blockchain.
Will busy users be rewarded in steem?
Given the above, Yes.
A just so slightly more technical answer what Busy/Steemit is in relation the blockchain:
I would say that for example steemit.com is to be considered a form of "open contract", that relates to a resource (The Steem blockchain).
You as a user can choose to use (sign) this open contract/steemit.com in order to access the Steem blockchain. If you want to and support it's maintance and developement.
By using steemit.com you accept the rules regarding passwords that most likely were displayed to you when you signed up ("The first rule of Steemit is: Do not lose your password") and up until recently there was also an info box for downvotes ("flags") on this user interface/contract, that informed you about what the "flag" ought to be used for.
... Now Busy, is another contract, where certain features such as flags/downvotes/smileys/goofey effects may have been removed/added to make things better for you as the person "signing the contract" each day by using the platform to access the blockchain. When using Busy, you don't need to consider any rules/guidelines given by Steemit.
Ultimately, it's up to you what platform you want to you use - or open contract you want to sign, so to speak.
Great answer. Thank you.
You're welcome.