Hemostats, they are sorta like locking tweezers. Better than needle nose pliers or regular tweezers for jumpers
Flashlight maybe.
Dont assemble it in a carpeted room if you can help it. Static electricity like living in them, but if you follow proper grounding procedure either with a ground strap, or always touching the case frame youll probably be OK.
Put the cats, if any, in another room 🙂
Depending on the case, band aids 🙂
Just take your time and double check everything. Nothing is cooler than when your baby you just built beeps to life.
And while it is a bad idea, ive used magnetic screwdrivers for 15 years on computers. Even when installing HDs. Dumb I am, I will be the 1st to admit it. But please dont use them, even if Ive gotten away with it.