Mitras Lightbar 3 for freshwater

Hello,

I have a ProfiLux4 running in my 180x60x60 planted freshwater aquarium. It has a fair amount of plants but nothing too demanding, my current lights are sufficient for a good growth.
Currently it is running with 4 AI Prime for freshwater but I am thinking on replacing them, mostly due to issues with the fans failing but also to centralize the control.

So I need some help in deciding what is the best light for my case if going with a Mitras solution.

Due to the fan issue with my current solution, I am leaning into 2 freshwater Lightbar 3 Skywhite. This should give me a bit more power than what I have now and also avoids having an extra power supply (since for this size, the 320W one can only supply 2).
Regarding this I have some questions:

1. I see that both the 170 and 180 sizes are good for my aquarium, is there a reason to chose 170 instead of the 180?
2. Is it better to have 4 90s than 2 180s?
3. Since I am thinking on only 2 lightbars, should I go to both Skywhite or have one as Ocean Blue? What would be better for the plants? I never played much with the colour of my light.
4. How high from the water level can I keep them to have light penetration for around 50cm of water height (in some places is 55cm).

The way I have my current light suspended, I do not think a Mitras LX could be installed the same way (due to its weight). But if that would be a better solution for my use case, I might look into other solutions for installing them.
How many LX lights would I need in this case?

Sorry for the mess in the post :)