Congrats on the puppy! My Bentley is 14 weeks old as well. Our house training is going well. I am certainly no expert, but I can share with you what I have done with Bentley.
I have a small room in my home that I deemed the "den". It is where there is no furniture. Only the crate, food and water bowls, some toys, and a baby gate reside there. Most importantly, I bought a tarp. Yes, a full 9'x12' tarp. I covered the floor with it.
I did both pee pad and outdoor training simultaneously. And for the first week I did not let him venture out past the baby gate to the rest of the house. I took him outside every 30 min to 1 hour. I also taught him how to use the pee pads. Now, fast forward 6 weeks to today. He has, maybe, 1 accident indoors a week. And that accident is always on the pee pad or on the tarp where a pee pad should be (but now I'm trying to wean him off the pee pads...). In 6 weeks he has had 1 poop accident indoors. And has had 2 pee accidents not on the tarp. That's it. I plan to take away the tarp after he has no 0 accidents in 2 consecutive months in a row. Vigilance is the key. Watch him like a hawk!
As for the nipping. Golden retrievers are mouthy to the extreme! He is playing with the other dog. If he gets too rowdy the other dog will let him know. But you should learn to understand his growls and barks and mannerisms. Learn what is play and what is not. Then you will know when to intervene. I've heard, though have yet to experience, the mouthy behavior gets better after they teeth and lose their baby teeth.
I wish you luck! Sent from my iPhone using Petguide.com Free App