1 mineral spirts cleanes out all the lube, residue and stray particles in the bearing causing it to run smooth have greater sleep times.
2 you can clean a small bearing with the same method. just remove all the shields and c clips from the bearing like you would with a large bearing.
3 you do not need 1 drop from a needle. that method is prefered to add a small perfect amount of lube to the bearing. you can add lube from the bottle but it will come out in a big drop as well as fast as thin lube has the consistency very similar to water. if you do not have a needle how did you clean the bearing in the first place removing the c clips and shields. you can clean it with those things on but it is not guarenteed that all the particles will come out.
4 to remove the rust from the bearings you would need a cleaner to clean the oxide from the bearing that might potentially hurt the bearing. you could also go to a jewlery store and ask them if you could use the thing they use to clean the jewlery thru vibrations. however you should take a large batch of your bearings so your not wasting money on 1 bearing. if you do this you should suspend the bearing in the mineral spirts.
5 to take care of your bearings in yoyos do not keep string on for a long period of time. keep your yoyos in a cool dry place. humidity is BAD. always lube your bearings in a small amount after cleaning. and allow your bearings to break in and do not always just clean them