On a dropped third strike, you can score PB, WP or E. The batter & pitcher are both credited with a strike out.
If the ball is in the dirt and swung at, it's usually a wild pitch. If the ball is in the strike zone, you could call PB or WP depending on cross-up or just missing the ball. Almost always a PB. I would only score wild pitch if catcher is set up high and away for the 0-2 fastball, and pitcher throws a down and in curve that happens to pass through the zone. Very rare though.
In the case sited, if you think the catcher should've made the play with ordinary effort and simply dropped the ball, you should score E-2. You would do the same on the routine scoop, failure to step to the side and subsequent high throw down the right field line. Likewise if good throw is dropped by first baseman, score E-3. Just play it back in your mind, what would've happend with ordinary effort. If pitch was uncatchable, WP. If catchable, PB. If pitch is handled such that ordinary effort should've resulted in an out, give an error to somebody.
On the second question, I'd go with jfsbndr. Only thing to add; as described, I'd call it a pick off of R1, so he'd get credit for a caught stealing. I would not credit a caught stealing to R3, since he wouldn't have received credit for a stolen base since another base runner was already caught stealing on the same play.