The $500J adult / $100J children admission price is just that - just gets you in. (I looked thru my pics from 2010 trip and found sign with admission price listed.
The food, I don't remember exactly, but was reasonable - like $500-700J for a quarter chicken or pork plate with rice&peas, salad, and callaloo - less for just meat.
I guess the sound level is all in the eye (or ear in this case) of the beholder - I didn't think was that loud unless you were in front of the speakers.
You can carry on a normal conversation everywhere else on the property.
Here's a few pics from 2010.