I was doing some long overdue cleaning today and found that the passenger side boot on the steering rack has a serious split. Where is best source for replacement and how involved a procedure is this? Should that side be disassembled and repacked with appropriate grease?

The procedure isn't too involved; loosen the locknut and unscrew the tie rod from the tie rod end CAREFULLY counting the turns. Change the boot. Screw the tie rod in just the right number of turns, lock the nut.
Note there are 2 different rack assemblies, requring different boots.
Go to www.rprusa.com, click on tech tips, then on identifying steering racks to see which you need. Since you're there already, you can order the boots from them, though any Volvo parts supplier has 'em.
There's no grease, though the ZF racks are supposed to have 50cc of some mystery oil in the boot. I used Mobil 1 15W-50 'cause I had it lying around.