New Military tactics
«may discard this card from tableau for +3 Military this phase»
Can I discard this card without needing in this +3 Military? Can I discard this card and do nothing else, or discard and settle no-military world?
Yes (to all).
«may, as your action, flip a card: if it is a world, place it at 0 cost; if it not, keep it»
Is this mean that I can do this action instead of common settle? Not in addition (second world)?
Correct; that's what "as your action" means.