can you wipe clean with a damp cloth if needed?

Yes you can use a damp cloth. I use Weiman leather wipes to add a nice look, and somewhat glossy look to it.

What is the width of the actual headboard? Trying to verify specs. What is the distance from the bottom of the legs to the bottom of the headboard?

Yes, two caveats: (1) King means Eastern King 6’4” wide 6’8” long not California King 6’ wide 7’ long. (2) steel bed frames normally have horizontally slotted holes for headboard mounting because the frame has an adjustable width to accommodate foundations that aren’t precisely sized, padded edges, etc. The length of the slotted holes in the steel corner should be enough to accommodate the variation in foundation and headboard, but it’s possible to set the adjustable frame width an inch or two wider than needed to make it easy to put an idea than usual foundation on it and find there isn’t enough slotted hole. It’s possible to find a frames with larger corners and longer holes. Another option is to make a small adapter to shift the hole spacing. Either a pre-punched 1/8” thick steel flat bar or a short piece of hardwood 1x4 and tee nuts will work with similar effort. The hardwood has to be both cut and drilled, but cutting a steel flat bar without ruining multiple blades requires a little oil and some patience whether it’s a power tool or one of the traditional cordless (Armstrong) saws.

Will this work on platform beds? How tall are legs

I believe yes that the headboard will work. Multiple choices for height. Padded headboard piece is approx. 22 1/2 inches. The legs are 39 inches. There are 8 hole choice for adjusting height for the leg attachment to the head board. First hole on legs is 2 1/2 inches from top, then 7 more holes lower. The bottom part of the legs have approx. 4 inch slot to connect to the bedframe. So the important part for you is does your platform bed have pre-cut slot in order to connect the legs to the platform. There are numerous choice for height and very easy to assemble.