There should be a factory plug in the wiring harness on the frame rail ,that you can unplug,leave all the old wiring intact on the old bed..hopefuly the wiring will still be intact on the bed your swapping on ,so it can just be plugged it,no splicing !..
I've had to tack weld the heads of the bolts to the bed in order to get them to unscrew when I was alone ...I usually get new bolts ,most of the old ones wont come off with anything but a cutting torch after 10 years around here..I think I saw new bed bolts listed in the new Doeman parts catalog,so you wont be limited to buying from dealers or hardware stores..I'd avoid using cheap carriage head bolts that are only grade 2's ,get the right grade 5 ones if you need to replace them..
I have hoisted beds off with a come-a-long and a sturdy kids swingset,or hefty tree branch ,but now I have a home built gantry "A" frame to use..once my brother and I used his clothesline posts (made from 1-1/2" pipe) to lift a bed off his pickup!..I used a long chain bolted to each stake pocket as the lifting points,it keeps the bed level and makes it easier to manuver..I've used an engine hoist to pull beds off too..