Hi @vicaaciv,
these are good points, thanks for asking!
Every Blessing is valid for 3 days and Blessings don't stack their effect.
Example:
If you have 2 Queens Blessings you will have 6 days with a 20% bonus.
If you got 1 Blessing and you already used it for 1,5 days and you purchase another one you will than have 4,5 days of blessings left.
Note: Blessings that were rewarded/bought before the launch will start at the launch so it's safe to already buy them.
Hope that clarifies things, I will update the post accordingly.
For Steem we fight!
-@mwfiae