Side question: If I wanted to create something with poison, how would you do that, as there doesnt' seem to be a poison-based power from a glance through of the rules. Would that just give a larger Weapon effect to say, claws, but only works on biological things?
Depends on the type of the poison.
If it is damaging it could just be a bonus to the stress applied following a successful attack
If it's something that hangs round you could apply a Tag of POISIONED following a successful attack that you can then tag for the effect you want e.g
*If it anaesthetic that slows you down gives a negative to alertness roll (and thus initiative)
*Paralyse where you would be using grapple rules against the "might" of the poison- which would probably default to the stress inflicted by the initial attack(I.e. The amount of poison you got into them) unless set independently. (for "just one drop has the strength to kill a thousand people" style poison)
*It could be 'addictive' like the vampire saliva.
*Apply on going stress each exchange until the Tag is removed with a 'first aid' or 'recovery' type test. (e.g First aid or might check verse the strength of the poison)
Being Fate there are as many ways of doing it as their are poisons
work out the 'effect' of your poison and calculate it back from there.
Worse case treat it as a magic item : poison using the potions rules
see the example on pg 281 YS