Lots of info on the assembly pages about all of this.
Use the nutlock that fits your coupling nut. The time is doubled because I ship both with the kits and this is how I calculate price.
Pinapple coupler, all the info is on the assembly page again. Use the one that fits, are you using a 5/16 rod or an 8mm?
If you are in doubt print them all and use the one that fits it will only cost you an hour and $.20 worth of filament.