Just back from driving to Punta Rusia last week (and also driving from STI airport to Sosua).
1. Forget the Ruta Turistica. While you can do it in a 4x4/SUV, the going is so slow it takes longer than the main Navarette/Puerto Plata. It's a shame, it's the most direct route, has a nice mountain view from the top and actually would be a nice drive. (assuming there's a paved road there).
2. As cobraboy mentioned, the main Navarette/POP road has a lot of construction and several slow spots but it's a sure bet. Take it.
3. Going to Punta Rusia (assuming from the turnoff on the Navarette/POP road just north of Imbert), I did it in an SUV last week. No problem at all. Yes, there are bad sections (potholes) where you'll need to go slow over and yes, at points the road is real narrow so if you get stuck behind one of the tour buses you'll have to wait a bit until you can find a stretch to pass but otherwise, no problem. Note if you're going to Punta Rusia for snorkeling (paradise island), don't believe when you hear it will only take an hour etc. It's easily an hour and a half trip FROM the turnoff on the Navarette/POP road and can take 2 hours if you get behind slow traffic so plan accordingly. If you're going for the snorkeling, try to get on the road either early (by 7-8am) or later (12-1pm) to avoid the tour buses.
4. Haven't taken the Moca road so can't comment on that.