How to focus, meter, and stabilize a daytime coastal scene with a 10-stop ND?

[Isabella5]

I've recently gotten into long exposure photography, specifically trying to capture smooth, silky water effects in coastal landscapes during the day. I'm using a 10-stop ND filter and a tripod, but I'm struggling with getting sharp images and the right exposure length. For photographers experienced with this technique, what are your go-to camera settings and workflow? How do you calculate the correct shutter speed with such a dark filter, and what's the best way to focus and compose when the viewfinder is essentially black? Also, how do you handle issues like wind vibrating the tripod or dealing with bright highlights in the scene that blow out during the long exposure?