A 400w light will have an effective range of almost 3 feet. For young clones and seedlings, 2 1/2 feet is fine. Once clones are rooted, or seedlings are well-established...ok to start lowering the lights. (hardens them up to the increasing light intensity) After about a week of hardening them up, I keep my lights within about a foot, until harvest, but your ambient room temps will determine what you can get away with there.

In flower, I would take the fans off the light timer, if it's on the same circuit. With high humidity, you'll want the fans on 24/7. In flower, 70% humidity is not fine. The lower, the better. I live in the desert, and summertime humidity stays around 10%. The ladies love it.
In veg, the plants like humidity a tad higher anyway, but keep an eye open for mold, just the same.