Hi there! I'm getting married at Beach Palace in April 2017. I was told the same thing about the Palenque Terrace, that you have to bring lighting in. We decided to go into the ballroom because the $1500 fee was canceled out by the lighting required outside. Of course, I did that before I found out a dance floor is not included in the ballroom rental fee... but we decided to keep it just to ensure it's not too humid for all the dancing.
Regarding the Sky Terrace, I was told the speakers there are plug and play if you bring an iPod or something. I have a couple of events other than our reception, and I'm reusing some of my DIY elements (silk flowers, etc.) to add a bit of decor to those, but definitely not bringing in any vendors. One cool thing I saw a bride do when I went for a site visit was bring these floating lanterns for the pool.