The front wheel bearings are non-adjustable. They are a sealed bearing and hub unit. If you have play,they probably need replacement. You will have to pull them to do the ball joints,so if it needs it,might as well do them then. Be very carefull sliding out the axle shafts as the seals are very fragile. It also helps if you jack that side of the truck up higher so the fluid stays in the diff,or if your changing fluid,drain it first. Any lube that spills into the axle tube can look like a small leak until it dries up.
The pinion bearings can be checked on the truck,by trying to more the driveshaft up and down. If you have any play,they you may be able to adjust it. They should also rotate smoothly with just a slight drag. Only real way to check them fully is to pull the pinion out,and inspect them.
Any good synthetic fluid will be fine in the diffs,but you may have to add some friction modifier to the rear if you have a limited slip. I use whatever synthetic I have on hand,all have worked well. Do a search on diff lubes,and you'll find lots of good info.
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