If you do not want to mess around with teenagers and broke down cars then I would hang everything but the knock sensor. If the pressure regulator or the engine speed sensor take a dump on the road usually no amount of pounding on them is going to get you home. Make sure you replace the correct suppression relay as certain year models run a pair of them and one will leave you stranded and the other will make it so the auxillary fan does not come on. Just pull the relay while the car is running and if it keeps running well then it must be the one on the other fender. The only thing that comes to mind that is not on your list is the power stage.

Mark

When you are next at a junkyard with Volvos, pick up some spares for these parts (make sure they are the same system) as well as an air mass meter. It's nice to have them on hand if something fails and needs to be tested.

Sure, any of them can go south without notice, however the fuel pump relay is the #1 failure component of those in your list. When they begin to go, you can usually just tap on them from the driver's seat and get home. If your kids know where it is located, behind the ash tray second row first on the left, they can get it going. I have my son re-solder the connections in them and they last forever.
Jon