Set COUNTER to X - unaware of any way to do what you are describing.
UNFLIP ALL - no code way to do this, but you can drag a box over large swaths of the play area and flip them. I built a flip function to do just that.
PLAYERSTAT +/- 1 - this can be done and can be made in the macro button area by counting the player stat number and referencing it with a + or -; for example
!Won!/p+1 would set playerstat 1 +1.
FACEDOWNVISIBLE - This can also be done. Look in the plugin tutorial at the MULTIPLECARDBACK features. In the plug-in I built, I have facedown cards that are visible to the owner (but could be anyone) simply by hitting shift; in a similar fashion that a player may peek at their cards on the table and then place them facedown. This method will flip all cards built in that fashion that the owner can see. If it is set to all, then using shift will make visible all such cards.