High Rock Spring is about a 5-7 minute walk from the buildings in Congress Park at a leisurely pace. That's about the same amount of time it takes to get from a room in the Beach Club Villas to Stormalong Bay. If you don't wish to walk, you can jump on ANY theme park bus circling the complex and get dropped-off right outside the pool in about 30 seconds.
The pool will be open when you visit and all WDW pools are heated. Whether you decide to swim is up to you. The weather could get as high as the 80s during that time of year, although upper 60s/low 70s is more common. You'll have to check the forecast and plan accordingly.
IMO, there is no noticable distraction from Downtown Disney when staying at these buildings.
The rooms have been specially designed to insulate much of the noise from the fireworks. With doors and windows closed, you won't hear more than a slight pop outside. In the 5 nights we stayed, nobody from our party (3 adults, 2 children) was awakened by the fireworks. Oh, and they only last for about 30 seconds.
