How tough is it to change the half shafts?

About an hour per side once the van is on a hoist and all the tools are at hand. You'll need a really long pry bar. Mine is almost five feet long. You'll also need a click-type torque wrench that goes really high. The axle nut requires a very high tightness and it must never be loose while there's any weight on the wheel bearing. Doing that will make them instantly noisy.

If a rubber boot is torn on an outer cv joint, they can be replaced for a much lower cost than for replacing the entire shaft, but you'll need some special tools. Many auto parts stores can borrow or rent them to you.