Yes, they can be seen. I am not sure if the music is still piped in though. I see no reason not to bring your beverage to teh beach, but again, I am not sure.
Yes, MNSSHP fireworks viewing can be seen quite well from the beach - it's a good "straight on" angle. I have not seen any reports this year about MNSSHP show audio - I assume it is playing just like it does for the regular Happily Ever After Show, but not 100% sure about that. It has in years past.
I am pretty sure the music is still at the beach. I watched Halloween fw from the Contemp and from the boat dock at TTC and both had music. No reason why they wouldn't for the Poly too.
We loved watching the fireworks from the beach! It's been a while since we have stayed there, but they used to pipe in the music. DH, DD and I all enjoyed it.
I had a lovely Lapu Lapu drink to accompany me, it's a must at the Poly!