I was also wondering, for setting traps (like a firebomb set off by a light switch), would she also need the Juryrigger quality or would the just the Demolitions skill suffice?
Going by the various tests mentioned in the Blow Up Good chapter of Run & Gun, Demolition is seemingly used for all kinds of improvised explosives, but other skills are mentioned as well. Thus, as a GM I would likely make you roll Hardware or Industrial Engineering (or some other appropriate skill) to rig up any device not intended to be used for demolition, such as the light switch in your example.
Examples:
For a car bomb to be effective, it needs to be able to destroy the body of the vehicle in which it is hidden (typically the trunk, on/near the engine block, or planted on the undercarriage) and still have enough power to cause damage to the surrounding area.
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A rigger needs to make an Automotive Mechanic + Logic [Mental] Test, with each hit reducing the Armor Rating of the vehicle by 1.
Turning a commlink into a radio detonator requires two tests: a Hardware + Logic [Mental] (4) Test and a Demolitions + Logic [Mental] (3) Test.
Turning a commlink into a makeshift timer detonator requires two tests: a Hardware + Logic [Mental] (3) Test and a Demolitions + Logic [Mental] (3) Test.
All of that being said, page 195 lists Electrical Detonators as being used in booby traps "by being wired to things like a light switch, a trideo set, or a vehicle’s ignition", but it also states that a strong electrical pulse is necessary. A light switch may or may not have enough power, at which point you'd need to wire in a battery, which to my mind would be a Hardware or Industrial Engineering test (either would work, no need for both).
Oh, and don't forget: Bullets may have someone's name on them, but sending 20 kilos of ANFO is more "To Whom It May Concern".
ANFO is for amateurs and home-grown terrorists; C-12 is where it's at in the 6th World.
And while bullets may have your name on it and 20 K's of C-12 may be more of a "To whom it may concern", always remember that a Thor shot is a public declaration...