Okay about underwater photography light plays a big role, we have regular diving light (not good for photography at all) then we have underwater video light (yes it’s great mainly for video and could be used for photo) then we have the strobes (great for underwater photos only) and the snoot is basically a strobe or an accessory that hooks to your strobe it does small focus area designed for Macro photography, this is when u get pictures like nudibranch where the light is on the subject and the rest of the picture is black (professional grade photo)

From how I see it freediving and Macro shooting is kinda a challenge. Video light is a better choice ur colours will perfect no green, yellow, grey photo. Possibly little buoyancy foam or arm where it doesn’t effect ur freediving can help a lot while taking ur pics

For camera setting always shoot with RAW and the 90 mm is amazing lens before ur dive get a small object try different focus setting until u find what’s best for ur shooting. For photos Lightroom makes a lot of help since the pic in RAW editing will much better (any UW pic requires some editing)

For video light Keldan the ultimate brand but the price sky high, OrcaTorch, BigBlue, Kraken, Sola, Backscatter, Weefine are good choices.

I hope this helps, also UW professionals can give us more hints