Congratulations, and happy to have been of service! All these things you mention are fairly easy (if sometimes messy

) jobs. I'm sure you are crawling the forums for info like I did, and that can be a bit of a rabbit hole, so allow me to save you some time based on my own experience and exhaustive research.
Go here for
@MScruiser 's excellent video's on diffs.
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- Before you change your diff and xfer case fluids, order some magnetic drain/fill plugs. Get the 14mm bolt head drain plug (part # 90341-24016) for your front diff to replace the impossible to remove hex head bolt.
-Use Amsoil 75W-90 in your diffs and you'll never be disappointed.
-Use either the Toyota LF fluid ($$$$) in your transfer case or go with the excellent, fully compatible, and much less expensive Redline MT-LV. If you have the dealer do your transfer case fluid, they'll likely use Valvoline gear oil and you will end up wasting time, money, and frustration getting a recurring "stuck center diff light" diagnosed.
-Spend the extra time to remove and clean out the PS fluid reservoir when you flush the system.
Good luck!