I'm going to try to gather all existing rules-related questions into a FAQ here. Going forward, try to post rules questions in this thread.
Q1) How do face-down resources work?
A1) When you want to play a card, you must have the proper number of icons in play. A face-down resource gives you no icons.
When you pay the cost for a card, you can use any resource cards you have in play and attach them to your faction. The icons on the resources no longer matter when you are paying the costs.
For example, if you had three face up Rage cards, and two face down resources, you could play a card that cost 3 and had three Rage icons, and a card that cost 2 and had three Rage icons. You have 3 icons in play, so you can play both the cards, and you have 5 total resources.
Q2) Are you allowed to respond with multiple cards/abilities before your opponent gets to respond to your response?
A2) No, in step 4 of responding, you play your tactic or ability. When you pay the cost, your opponet can respond. or not. or let your do 4 things and respond to the fifth.
Q3) What happens if a card tells me to depelte a card (Card X), and that card is already depleted?
A3) If it is the cost of a card, you can not pay all of the costs, so you can not play that card or ability. If it is the effect of a card or ability, then Card X stays depleted.
Q4) How do cards with a cost of X interact with cards that reduce numerical costs?
A4) If a card had:
COST - Pay X
EFFECT - Gain X Influence.
If you had played an effect that made your next numberical cost by 1, and you chose X to be 5, you would pay 4 resources, and gain 5 influence.
Q5) Is Zeron a number? Is it even? Is it odd?
A5) Zero is a number. Zero is even. Zero is not odd.