A mixed conifer border is a great idea for privacy sceening - more interesting than a single species, less inclined to spread pathogens or insect issues from one species to another, better for wildlife and if one dies, not an obvious 'hole' in the pattern...relatively easy to replace. A staggered or zig-zag planting will be visually more interesting than a straight row of conifer 'soldiers'. You might even want to fill in the gaps with some deciduous plants (more towards the foreground) to increase the visual interest.

Some of your proposed list are more/less tolerant of shade than others and growth rate will vary widely. Best to research each species you choose and decide placement and spacing based on mature spread/height and light and/or water requirements. Locate plants with similar needs together.

A few of those you listed could fill the whole area in time, just by themselves.

Unless you planted dwarf or slow-growing cultivars.

good point, if its only 20 feet wide, you might want to just pick two large trees, then plant some smaller evergreen shrub trees that can eventually work as an understory.

you may want to consider Umbellularia californica for a larger tree as well if you don't want all conifers.

Larger, indeed.