I'm planning to change out the lights in my pool. Currently have what looks to be a fairly standard large light in pool and small in spa. I want to install the Jandy WaterColors LED as I have the iAquaLink so I can control them discretely without the on/off routine to select colors.

My questions are as follows:

Are niche sizes standard?

The wiring for the lights seems to be the standard three wires. Is it possible to splice the wires from the new light inside the niche to the current wires running to the pool pad so that I don't have to pull the new cable?

I am hoping swapping out the lights can be done without draining the pool by pulling the niche out and redoing the wiring. Is this feasible or even possible?

Any other suggestions or things to consider?