I really only feel like doing one axle (making noise), but will it make more sense to do it all at once and not repeat steps? What if any special tools are needed? thanks in advance

It's almost cheaper (considering time etc) to have it done. I had both axles and boots etc changed for $179 per side. Took less than 2 hours total. The steering rack will entail having the motor supported while it get replaced.

I've not done the rack myself but a few people here have mentioned that it is a major pain in the ass.

My experience with axles/CV joints in front drive cars over the years has shown that if one side has gone bad, the other won't be far behind. I would do both and save yourself from a second trip under the car.