Has any climber ascended all of California's Fourteeners in Winter ? How many have been skied or boarded from their summits or as high as there is snow ?

All of 'em.

I can personally guarantee all California fourteeners have been climbed in the winter, some by a standard route, some not, some many years ago. I don't know about skiing, I skied up and down Whitney, Williamson, White, Shasta, Langley, Muir and Split in winter.

I read that Chris Davenport was attempting to climb and ski all of the 14000 ers in the lower 48
http://skithe14ers.com

Lou Dawson has also skied all the 14000ers in Colorado so far.
http://www.wildsnow.com/biography/lou_fourteeners.htm

As mentioned, many people have summitted all the 14ers in winter.

The ski/board question is a little more elusive, and somewhat intentionally so. There's a long history of keeping notable ski descents in the Sierra quiet. Of course, there are a few exceptions: the "Redline" guys on Whitney and Russell, Dave Braun's Couloir Magazine article on Williamsons Giant Steps, Plake on Split, Davenport's recent efforts, etc. But who knows the name of the first person to ski Middle Pal's NE face? I sure wouldn't claim to know who was first, but I do know the name of someone who did it. Or who skied all the Sierra 14ers in one month (albeit, not in "winter"... but that's a whole nuther debate) in 2010, the last one with a broken leg?

The point is, you won't find a readily available historical record for Sierra ski mountaineering. Especially not like you'll find for Colorado or the Tetons. So, I'm not saying yes or no, 'cause I have never heard of anyone claiming to have skied all the California 14ers in winter, but I am confident that there are many feats that have gone unpublished and have escaped my attention. And I feel fairly well versed in the subject.

In addition to no readily available yes or no answer, our history of mystery also saddles us with no standardized definition of a peak "descent". For instance, conditions conducive to skiing Middle Pal might happen a few weeks every few years. Do we wait years? Call it good from the highpoint of the glacier? What about North Pal? The u-notch gets skied all the time. But who goes to the summit? Does that count?

I personally have come to embrace the mystery. Mainly 'cause there's no other option.