It sounds very much like a scale type insect. Since this tree has exfoliating or flaky bark, I'd remove a portion that has a population of these spots/insects and take to your local extension office for ID and treatment suggestions. The good news is that the insect showing on the leaf is the pupal stage of the lady beetle (ladybug), one of the best beneficial insects you can encourage in your garden. Will take care of those pesky aphids lickety-split! Can do a number on the scale as well. Whatever treatment you are directed to, make sure it is non-damaging to the beneficials.

Chaste tree and other grayleaf plants would be less harmonious than others in similar shades of green to what you have listed as being in the planting already. I'd look into Italian buckthorn (Rhamnus alaternus), California lilac (Ceanothus)--these come in both tall and low--green leaved species of rockrose (Cistus), green leaved cultivars of sunrose (Helianthemum), things like that. Except for the buckthorn these all have plenty of flower power. And you can get the buckthorn in a white variegated version that might be quite pleasing with the pinkish color of the 'Marina' flowers. If you are near Seattle you can see Italian buckthorn in the hedge south of the parking at Good Shepherd Center (along with Viburnum tinus, another candidate to consider) or in the corner farthest from the entrance to Greenlake P.C.C. (near the black locust trees).

The Bremerton acacia shows signs of having frozen to the ground in the past and is of interest precisely because it is just about the only persisting one of much size known in the area. It is exceptional, like the azara in the UW Friendship Grove and the 50' eucryphia near Brian's place in Bremerton. Many others will have been planted elsewhere and frozen out in time. The late J. Witt of the Washington Park Arboretum once told me that there used to be a 50' eucryphia in a garden next door in the Broadmoor Golf and Country Club (most likely planted in the D. Graham garden) but it died in the awful 1955 freeze. An obvious difference between the two sites would be that the Broadmoor location is some miles from salt water, whereas the Bremerton site is quite close. If you are close to the beach the salt water keeps your minimum temperatures higher enough than even areas father inland but close by to make a difference in what you can overwinter. A cottage on Vashon just behind the Seattle/Bainbridge ferry dock has had a tall conspicuous abutilon for years. Even though this is a north exposure, apparently the salt water is keeping it from freezing out. I think I noticed it was still there during a recent visit even after this last winter, although the proof will of course be if it is seen blooming and full again this summer. One of the better embothriums I've seen was growing right behind the beach along a quite inlet west of Tacoma. It was the first bit of plant life behind the cobbles and sand, and was leaning towards the water as though responding to its proximity.

There's too many azaleas only if you want one or two plants of each kind in the entire planting. Otherwise, since the azaleas are small-leaved if anything the planting could stand to use more of them, to balance the leaf sizes of the nandinas and in particular the palm. (Also I would stop clipping them so they stand apart from one anther like tombstones, would instead allow them to merge and form a drift). Windmill palm, heavenly bamboo and evergreen azalea all want more moisture than manzanita. And look the part. So if you stick a manzanita among these others there will be a conflict of naturalistic character. 'Howard McMinn' is good looking and has made some nice specimens visible from Seattle streets. And elsewhere, including at the Rhododendron Species Botanical Garden in Federal Way. However it also has a tendency to develop leaf galls here, and for whatever reason the still recently good looking example at the Rhododendron Garden had suddenly gone south the last time I looked, been basically lost - perhaps to crowding and shading. If you start planting types like manzanitas you are dealing with dry-land species that have little tolerance for shade and dampness or heaviness of the soil, at least in the case of the last two them occurring in combination with one another. Think coastal California and Mexico, the Mediterranean etc. Whereas what you have planted in that driveway bed now is E Asian monsoon climate species, from places where it rains buckets all summer most years. If you now want to focus on dry climate plants instead I would take out the palm etc. and probably replace the soil in the bed with a coarse one prone to excessive drainage. One time I bought pit run sand and dumped it on top of the existing soil in front of my house, made berms which supported an assortment of plants that all did well (although few of them were actual dry-land kinds, I am sure it would have worked for those. And I wouldn't have felt the need to water them in summer). Also at the Jungle Fever Exotics nursery in Tacoma there is a berm between the sidewalk and the sales yard planted with things not usually expected to grow here, consisting visibly of some kind of freely draining or otherwise "different" soil that is making it possible for these plants to persist. Bing Images - Jungle Fever Exotics Nursery http://www.bing.com/images/search?q=jungle+fever+exotics+nursery&qpvt=jungle+fever+exotics+nursery&qpvt=jungle+fever+exotics+nursery&qpvt=jungle+fever+exotics+nursery&FORM=IGRE