Think you'll get more responses if you start a new post in DESIGN. This forum is really slow. Some additional pics to show the property might help too.

HTH, Rosie

Color all year round is hard to get, except with annuals. Most perennials bloom just once a year.

However, there are a few that might work. Some roses (like Knockouts) bloom fairly continuously. Ditto Rozane geraniums and some daylilies. Gaura has a long bloom season. These all die back in the winter, however.

You could do low-growing/groundcover evergreens, for year-round green, with perennials selected to bloom one after the other. Macrobiota would be one evergreen possibility.

I am planning to add some barberry shrubs and vieragated rhodos, forsythia and flowering currants for spring, pinks are great beside the daylilies I have down there too! I am planning some shrub roses too!

You are headed in the right direction with the variegated shrubs & the shrubs with color(barberry). You still will have color & texture using different shrubs & mixing in perennials with different bloom times.For your constants, I would throw a few annuals in there too.I like to call them "tweeners".They tie the perennials together, when one finishes & another begins.As for the bottom, looks like retaining wall material to me.If your on the cheap, you can just use large rocks, which looks like you have access to, to line the bottom of the hill.this will hold back any soil that will wash down.Looking forward to seeing your progress.

i agree with calamity you can add some barberry shrubs and vieragated rhodos. you can retaining hill with the woven geotextile

Here is a link that might be useful: woven geotextile

Also there is cotoneaster (both green and variegated). They are shrubs that are lower, with an arching, spreading growth; and though they are deciduous, they have berries to add interest (and attract birds) in other seasons.