you'll be able to read tons of posts on these two subjects if you use the SEARCH on this site.

Yeah, you can change oil, Mobil 1 is the oil to use. Things like how often you had oil chenges in the past can effect getting some small harmless dripping.

Ball joint - raise wheel and hold tire at 12 & 6 and shake for play, I think that is the method, Should only get a few millimeters of movement. A few centimeters shows worn joint. But you better double-check in the SEARCH.