Hardware and Fasteners - Anchoring bookcase to metal stud wall

I need to anchor a bookcase to a wall with metal studs and I'm not sure how I should do it. The wall is a fire-rated party wall, with I believe fairly thick drywall (5/8" at least), metal studs, and insulation (fiberglass I guess but I'm not sure). This is in a child's play area so the bookcase needs to be anchored pretty firmly to avoid disaster.

Should I use fine-threaded drywall screws into the steel studs, or some kind of drywall anchor? I'm not sure if toggle bolts will work because of the insulation in the wall. Thanks for any suggestions you can provide (and Happy 4th!).

I would use a wide head cabinet screw. Most screws will self tap into a metal stud, so with a little pressure it should work. The wide head is necessary to keep the cabinet backing from pulling off the head of the screw. This is just a tilt preventative measure, right?

This is just a tilt preventative measure, right?

Yeah, the book shelf will be sitting on the floor, so this is just in case somebody decides to try to climb the shelves (which I expect is bound to happen sooner or later).