Never heard of anyone rooting a broken Phalaenopsis spike. You can put roots on a kiekei. Very few orchids are rootable by cuttings, a few Dendrobiums are, Restrepias can, Catasetums sprout plantlets along the pseudobulb sections are laid on a horizontal bench.
You can get new plants by seed, by meristemming or cloning and you can get new plants by vegetative division.
As far as your spikes go, if they are endangered by people or animals brushing up against them they snap easily, I would stake. But honestly it is up to you. They will be very unlikely to snap a plant in half.
Cutting back on a old spike to a node will produce new buds. Advisable to only do that on a mature plant. If you grow your Phalaenopsis in night time temperatures that are too warm, you increase the percentage of getting keikis.
Frankly I prefer a staked Phalaenopsis spike to a point and then let the upper section curve gently. This displays the flowers to their best advantage and allows the viewer to see and appreciate them to the fullest.
