The lobby Dolphin bar is open until midnight and looks like a great time. I am not sure about the Fountain but if you download the Swan Dolphin app on your phone and click “here now” you will get the most up to date info. Picabu I was open this morning.
Bottled water- I did go the front desk and asked for all the bottles for the next day. They happily bagged up 8. You can also call housekeeping for these.
Bus situation-
You are allowed to use Disney transport and it’s not that busy this week so walking to the Boardwalk or Beach Club area would be okay. If the resorts were very crowded, I’m not sure how I would feel about the Swan/Dolphin people sharing the bus. That said, I admittedly used Boardwalk transportation several times. At the end of the night when leaving a park, I jumped on either the BWalk or BC/YC bus, whichever came first. I took the boat back to S/D just for fun.