Regarding the bearings: The inner bearing inspection is simple. The cone just falls out once you remove the seal. The outer bearing is a different matter. I see that you have the manual so read it carefully. But as I recall it is not entirely clear. I did this recently. Here's what I remember: It turns out that it's a good deal easier and more stable with the drum attached to the hub.
First remove the inner bearing cup (outer race). 2) Using a hammer and suitable punch knock the outer bearing cup away from the snap ring just enough to release it from the ring. 3) With a STOUT pair of snap ring pliers, remove the snap ring through the inner bearing-cup seat. 4) flip the whole affair over and with a smallish punch that will fit through the axle-cap bolt holes find the cutaways in the hub casting giving access to the back of the cup. Not every bolt hole will line up so experiment al little till you find three that do at 120 degree intervals. 5) tap the bearing cup out of its seat and the bearing assembly will fall through the hub onto the bench.
Inspect the bearing. Finding it to be OK, reverse the above procedure. Once the outer bearing cup is retained by the snap ring, knock the cup against the snap ring to the bearing adjustment won't change under tension.
The original barrel-roller bearings are no longer available but tapered rollers work just fine. They are not necessarily better.
As usual, the second one should go much faster.
Note that the hub is designed with a shield on the inner side to duct any leaking oil out to the back side of the wheel not into the brake. If you don't clean this out, oil will continue to leak out of the shield onto back side of the wheel and you will think it's leaking again.
