token holder
https://www.thingiverse.com/thing:3385212
other parts 
https://www.thingiverse.com/thing:3241018

1: yes.
2: both dice, they're entirely independent of each other.
3: they stay red.
4: It's correct.  It's less costly to flip a card face down than to remove it altogether, one just removes the crit effect, the other is effectively damage regen which is very expensive and limited by design.

Resolve dice is almost always a may option.  Some card effects will require you to resolve, but the basic Resolve Dice action allows you to resolve one or more of your dice showing the same symbol.  So long as you resolve one dice, you do not need to resolve all of your dice showing the same symbol.  You could do this to save some for later in the turn, or maybe you're holding a card that needs to have that symbol in your pool to use (like Guard and melee dice).
At the end of the turn, during the Maintenance phase, any dice still in the pool get returned to their cards.