I have seen the fireworks from one of the beaches there, on the hayride we went & watched them. It's not like viewing them from the Poly beach, but still visible.
It does not take an hour for the boat to get to MK! We haven't stayed there since 1998 (3x there to that point) But,what we did then & all things are subject to change with WDW - We walked about 1 minute to a bus stop. Waited about 5 minutes for a bus to the restaurant/store/marina/dock area (Settlement?) From there, about a 2-3 minute walk to the boat dock. Then about 5-10 minute wait for a boat. about a 10 minute boat ride to MK. So, about a half hour average. I suppose if you had supremely bad timing, it could take you closer to an hour, but that would be rare.....
I can't answer your other questions as it's been 7 years since our last visit there. Bikes were cheap. Golf carts were expensive.
We did love FW Cabins & may stay there in Dec when we take DSS & family, including grandchildren. It's a great resort for young kids. Enjoy!