Hey, welcome back.

This project looks fun. I'd suggest posting some screenshots with measurements. The camera focal length and film back should match the real camera and using some assumed measurements the set can be worked out around those. What scene scale are you using and how tall is your figure?
As for the water, there is probably no reason to do a fluid sim. Just use geo or a texture there are no ripples and it's a still image. I'd worry about more important things first... Modelling the set.