For Zup to update DF, it would require making it impossible to play for older devices, this is not his choice, but from Apple, etc. Thus there will be no further updates to DF.
Also, DF Elite will never be done, there will always be tweaking because of players saying "what about this? what about that? can you add ___? can you eliminate ____?"
I don't know anything about mini-df. You can always email echoboom and ask them.