Underwater light for fiberglass pool

[m4gnumek]

Hello. I have an inground fiberglass pool. I am planning to install an underwater light, since all the battery or solar powered light do not last. I got a Pentair Amerlite light that's rated for 100W/12V Part# 78414100. I also have a electrical box located just 2' from the pool that is wired through a 12v transformer (I assume the previous owner planned to wire a pool light there). The Amerlite requires a big hole to be drilled through the fiberglass pool and I am not sure if it's suitable enough for a fiberglass pool or it's better to buy one of the new smaller lights.

If Amerlite will work. I would need to buy a niche but I am not sure which one should I get. I tried to reach Pentair multiple times but no response. I talked to 3 reps at Inyopool but all are recommending a different niche, two reps linked a niche that is rated for concrete pool, 3rd rep said that I should not use it with fiberglass. The part number that they sent is 79206700. Not sure if I can use plastic or I should go with stainless steel. I would really appreciate if you could recommend a niche to use with the light.

I want to add a led bulb with multicolor option, are the ones from Amazon good enough?

How would I install the niche? Do I just mount and seal it to the pool and run the wires to the electrical box, and it will be sealed already, or would I need to run conduits all the way to the electrical box?

Thank you!