First, improving ISO can improve shutter speed, but relative noise will affect image quality. It can be ignored with a full-frame machine. The high sensitivity control of the full-width machine is still very good. You can also increase the shutter speed by opening the aperture. For example, if the aperture of 1.4 is set to 400, there is no problem.

Secondly, here is a formula for you. Flash index (GN)/ distance from flash to object (D)= aperture value (a). Satisfying this formula, a normal exposure index can be basically obtained with a flash.

Third, the same as above.

As for whether to change the lights, it depends on your needs. After all, Yongnuo 560 does not support automatic metering.

I used Maze's 58AF-2. Nice color temperature