I picked a broken bike from the garbage around the block. The bike has some damage. It looks like a stolen bike (spray paint awfully over original color), so it must have had some tough love. I have identified the brand and model from its parts but no one has reported it stolen, yet. It will turn into a restoration job soon.
I am not the sharpest bike wrench so I could use some advice. Most parts are in good state. Obviously it needs new brake pads and new tires, and most probably a new chain, as this one is full or rust. The rear derailleur was so bent into the spokes that it broke. Definitely needs replacement by a new one.
The work that needs to be done on the rear wheel is not clear to me. The spokes are unbroken but it needs truing. I found it with some of its bearings opened, the ones on the non-driving side. When looking inside: not much contamination but some of the balls seem to be missing. I already have grease. Can I just buy any balls bearings? How do I know how many I need? Also the lock ring on these bearings is crooked? See pictures. Will it close? Or do I need a new one? Is it needed to buy a new axle + bearings? Is it simpler?
Here are some pictures https://i.stack.imgur.com/AWN0X.jpg