Cupressoid conifers - hard to identify

TPP is working on an expanded dichotomous key for ornamental conifers that can be cultivated here in the upper midwest.  It's only to genus right now, but it's for people who see a conifer of any sort and just say, "pine tree".  There are some tricky bits and it's always those darned cupressoid conifers.  The problem is always the same, if you've got cones, it's easy, but if you rely on just vegetative features, then it can be darned hard, and that's what you have to count on.  The biggest problems are distinguishing Thuja (arborvitae) and Chamaecyparis (false cypress), although distinguishing Taxus (yew) and Cephalotaxus (plum yews) is hard too.  Taxus baccata is tough enough, but T. cuspidata with very 2-ranked foliage is even more like Cephalotaxus, so TPP is so happy Torreya doesn't grow here to further complicate things; this genus has been put into both families in the past but is currently with the yews.  This still needs more work because those darned taxonomists have taken Chamaecyparis nootkatensis and transferred this species to Xanthocyparis so TPP's garden diversity just went up a genus, but some of the observations were based on his nootka cypress so no idea how to distinguish this genus from Chamaecyparis.  Also trying my hand at distinguishing Siberian cypress (Microbiota) from spreading junipers (Juniperus); this seems pretty weak right now, and you hate to just say red cedars are prickly.  At any rate here are some couplets extracted from the whole key to see what you think.  So rush right outside and see how these work. TPP thought he had the plum yew figured out until he took a good look at his upright cultivar of a plum yew whose leaves are helically arranged.  Siberian cypress and plum yews are some nice low spreading shrubs that grow well in light shade, and the former is hardy to zone 2! 

3.  Leaves green beneath, apex of keel leaves convexly rounded such that apex points inward toward stem, lateral lvs do not meet to form a seam; cones oblong, scales thin  .................................................... Arbor-vitae (Thuja)
3'.  Leaves whitened beneath, apex of lateral keel leaves straight or concavely curved such that apex points upward along stem axis, lateral keel lvs meet to form a distinct, sometimes white, seam; cones round, scales thick ……….……………… White cedar, false cypress (Chamaecyparis)
 
4. Rounded branchlets; awn-shaped lvs stiff; shrubs to small trees of various sizes ...…. Red Cedar, Juniper (Juniperus)
4’. Slightly flattened brachlets; awn-shaped lvs flexible; low-growing shrub up to 60 cm (2 feet), usually less than 25 cm (10 inches) tall …………... Siberian Cypress (Microbiota)
 
14. Dark solitary seed surrounded by green aril turning pink-red with maturity (only on female plants); lvs more or less 2-ranked horizontal branches; common. .............Yew (Taxus)
14’. Ovules oval, green maturing to golden brown (edible); lvs strongly 2-ranked on horizontal branches; rare................................…………Plum Yew (Cephalotaxus)