I don't know about yours, but my rig came with those square-bit screws. Exclusively. Except for the few the PO put in, which are an ugly mix of slotted and Phillips.
But yes, glass fuses and a fuse puller are very important to have, as are stop/turn/taillight bulbs. I like to have one long spark plug wire, as wires can go bad or melt at any time, along with Griff's suggestion of ballast resistor, voltage regulator and ignition module.
And, thanks to experience, I insist on having at least 2 lug nuts on hand as well.
