Hi Big Sur. I've been a carpenter since 1973. I built my 16' primitive Mongolian style yurt from scratch, using a simple plan I found online at 'clan yama kaminari mongolian yurt'. My platform (standard 2x deck construction), yurt, and cover cost me ~$1700, and about half a month of full day labor, including all the sewing. Yurt companies earn their pay.
I'd say if I can do it, another experienced carpenter certainly can as well. As to size, if I was building one to live in full time, I'd consider a yurt of 18' over my 16'er. IMO, 20' would be plenty spacious. Regarding wind, DEFINITELY anchor the yurt to the deck, and to the ground as well. Wind destroyed my first yurt that was unanchored.
For a primary residence, consider insulating under your deck and under the cover as well. I have nothing to offer as to
materials that withstand the damp coastal climate. We have friends that live north of San Francisco near Jenner/ Fort Ross area, and mildew is a problem there.
Feel free to PM me for other info. Good luck.