Tali

When using Cold Snap ("Choose a direction. Move each enemy unit in radius 1 space in that direction, if able"), do all units move simultaneously, or does Tali decide the order in which the units move? Example: Tali has two minions in radius in a straight line and chooses a direction in which, if she chose the order, one minion would be unable to move but the other would move.

Since it's the same clause, it happens at the same time.

If Tali places her totem next to a friendly minion, can it still be removed? Does it only prevent "defeat"?

Apply the text exactly as written. Removed and defeated are two separate keywords.

Does Tali's silver allow me to discard a color card even if it has been resolved already? Page 10 says "unless specified".

It's right there in the text. Read the full text. 3rd sentence.