Puerto Plata is about a half hour away from Sosua and about 45 from Cabarete, depending on how you get there. It takes a little longer on the gua gua!
Of course you can catch a cab. Playa Dorada has taxis all over the place. Careful with those prices though, they try to get as much out of you as they can. You can also get to Sosua by walking to the entrance of Playa Dorada, crossing the road and waiting for a public car. For 20 pesos you can get from Puerto Plata to Sosua in the day time. For Cabarete, I always take the Puerto Plata - Rio San Juan bus. You can go to Sosua on that bus as well for the same 20 pesos or to Cabarete for 30.
The beaches are different. Sosua, in my own opinion, is the nicest. It's just a beautiful beach and the water is great for swimming. It's generally the place where people go snorkelling and diving or things like that. Cabarete is a nice too but being the big kitesurfing spot, you'll find the water to be pretty rough for the most part. Not as nice as Sosua for swimming. Playa Dorada is well....nothing incredibly special. I only go there if I don't have the time in the day to go to Sosua.
In the Playa Dorada area, I guess the most popular bars would be Hemmingways and Mangu. A new one opened about a month ago called Roadway and they have some fun theme nights from the signs I've seen, but I've never been there at night. The prices are ridiculous for dinner though in both Hemmingways and Roadway. Mangu is just a dance club. A good place for dinner that I'd suggest would be Cafe Cito. It's not right in the Playa Dorada complex, but it's pretty close. It's about a 5 minute walk to the right after you leave from the doors of the Playa Dorada. Right in between Avis Rent-a-car and Harrison's. The food is great and they have everything from poutine, shishkabobs to filet mignon and lobster.
Guess that's all I can think of for now! Enjoy your honeymoon. And congratulations.