Peter's list is pretty comprehensive; I have only two additions to suggest. As part of the swivel rebuild you should consider new swivel pins and bearings, as well as seals. You'll also want to include lubricant of your choice for the swivel internals. The two main options I'm aware of (although there may be others) are oil and grease. I've heard arguments for both and used the
one-shot grease when I rebuilt my swivels. Soak the tube in some warm water before opening it to reduce viscosity and make it easier to apply. The swivel rebuild was fairly straightforward and I was able to do both sides in less than a day. The result was much improved handling. That project, coupled with the bushings, bearings, and TREs will get you many miles of safer and more responsive handling.
Having done all these repairs at various points in my Disco's life I'd recommend planning to have your truck off the road for a few days. If I was going to tackle all this at once I'd probably approach it in this order (once all parts and tools are on hand):
1. remove radius/trailing arms and do bushings. If you don't want to do this yourself find a local auto shop with a hydraulic press. They can press out the old bushings and press in the new ones faster than you'll be able to do this with home tools. Although you can do the removal yourself without specialized equipment. While the arms are at the shop you can continue to work on the other tasks.
2. at this point the order doesn't matter - hubs, swivel rebuild, TREs. You have to remove the hubs to rebuild the swivels and you need the steering links off to do the swivels, so you can pick the sequence once everything is apart.
3. after putting it all back together again it's a good idea to get an alignment done. Again, this is something you can do yourself but for the $70ish a shop will charge you can decide whether the time or money is worth more to you.
There are some good write-ups on this site that can get you through these projects, plus the technical manual is a good resource if you don't already have it (RAVE) for torque values, diagrams, sequence, etc. Use anti-seize and threadlock as appropriate so you'll have an easier time servicing these parts (or reducing the need to do so) in the future.
