For the seats, I'd enlarge every hole to the correct size, It makes it much easier and you won't have problems bolting it down. The bolts that hold the Ranger seats down are larger than the holes on the explorer seats so just enlarge them to the size of bolt you take off of your stock seats and you'll be good to bolt them down. Wiring is two wires per seat. A black and a blue wire. I connected the power wires into 1 and then ran it through the firewall with a 30 amp inline fuse. Ground is directly on the seat track itself bolted to the floor
For the seatbelt, completely ditch the way they're mounted the seat once you get them.
here is what I did, I found it on a website but I can't find it now but these are my seats.
Enlarge that 2nd hole, as u can see the metal shavings under it. Then go to the hardware store and find an appropriate bolt, washers and nut for it.