The quickest way to Epcot is to walk out of the BCV building, and make your first left. Follow that path around the building, to the right. You will end up on the main walkway to Epcot. This saves time, probably a few minutes. I always found it to be really nice at night coming home from Epcot, when you are tired and carrying a child. However, in the dark it sort of sneaks up on you, often times we walk right past the little gate.
Our last two stays at BCV we were firstly on the woods side, 4th floor, and did have a VERY partial view of the fireworks. From the 5th floor with a wood view, I believe you have a decent view of fireworks. We found ourselves in Epcot most nights for the fireworks, so this view did nothing for us.
Last year we were on the 2nd floor in a 2 BR overlooking to quiet pool. We had a HUGE balcony, it ran the length of all 3 rooms and we loved it. I also thought the ground floor rooms on the pool side would be nice, b/c what you give up in balcony you make up for in convenience of access to the pool. No elevator, just go from your living room into the water!
You will have fun no matter what you end up with. Enjoy.