They sell brackets for this.. sometimes they just behind where the washer opens with rubber mounts.. can get small ones or ones that are just about the width of the dishwasher… or can go cheap and use some rubber shims tucked out of sight lol

Return bro, better to be safe and just get a new one

Get a new toilet… most toilets even come with an all in one tool you can use… may need a crescent for the old bolts tho… would suck to come home to a layer of water over the floor

Assuming you just want it center… Get a metal receptacle and the light fixture your putting on…first turn off the power to your house, or designated part of the house…drill a hole center and big enough for your receptacle, strip your wires if needed, than run them through the receptacle. Secure the receptacle in place and if you can pull some slack enough to secure the wire safely out of place.. now get your fixture, wire accordingly, color wires can vary were you live, secure your fixture to receptacle put in light bulb, and your done… just how i would do so anyways, not sure if thats what you asked for lol

Easiest would be a metal/steel plate