For Diff, look down a few posts.... "2010 DIY Diff Fluid Change" I posted a ton of info on the rear Diff, Rear Clutch, Front Xfer/Diff. Very confusing info out there. Did a lot of searching and spoke to a few Parts Dept. Guys to get the info.
As far as other fluids, its recommended to Flush or at least Suction out the Master Cylinder every 2 to 3 years. Brake fluid absorbs moisture. You can not see it, but it does affect the brake components in the long run if it is not flushed. There is a very good product called MOTIVE Flush Kit. Very easy to flush the brake fluid with 1 person if you are a little handy... I also posted a detailed write up last year.
Power Steering, again a very simple process, get a cheep suction tool at an auto parts store, Suck out the old grimy black fluid, and replace with clean fresh amber or clear fluid. The reason it is black is from all the contaminates it has absorbed. You don't need to do a complete flush, but you will get at least 90% just by sucking out old and replacing with new.
Hope I answered your question....