Grosvenor used to be our home away from home until we joined DVC two years ago.
The hotel was slipping the last few times we stayed there.
But yes, if you have a tower room that faces the parks, you can see EPCOT fireworks from your room.
You can also see Pleasure Islands, but theirs only last about two minutes, at midnight. Not worth staying up for. But yes, you can see EPCOT's. You won't be able to see the water fountains or Earth spinning, so there is time when you see nothing.
If I remember correctly, there are two double beds in the tower rooms. One time we had the two beds and a day bed. So that room would have slept five. But out of all the times we stayed there, we only had the day bed once.
If you have any other questions PM me and I will be happy to answer your questions.