Res Arcana

You may take essences from any of your components, but if you take any essences off a given component you must take all of them (you may choose which components to take from). (p.5)

No — once a component is turned, you may not use its powers until it is straightened, except for some React powers which can be used while turned (unless the power’s cost itself requires turning). (pp.6–7)

Yes — discounts that reduce a placement cost are cumulative, and if a cost is reduced below 0 it becomes 0. (p.6)

The first player to pass takes the First Player token (worth 1 point at victory check), swaps their magic item for a different one (flip the new item to its Passed side), and draws one card; once you pass you can take no more actions that round, you ignore Life loss, but you can still gain essences from rivals’ powers. (pp.8, 5)

Each rival must lose the indicated Life from their pool; for each Life they lack they must instead, if possible, lose any two other essences (including Gold); players who have passed ignore Life loss. (pp.7, 8)

Discarding is from your hand (tuck the discarded card sideways under your deck as your discard pile), whereas destroying removes a card from play and puts it in your discard pile; any essences on a destroyed card are returned to the supply. (pp.6–7)