I am a really big fan of scoria or pumice in a trough mix to not only make it lightweight but keep it permanently oxygenated/draining well, so you never have to worry about wetness.
Most folks don't fertilize troughs unless that trough is for very hungry plants (like Aquilegia, or bulbs) or they are gardening in a really wet climate.
Containers getting bone dry in winter is a real pain... I struggle to keep an eye on them because they seem to go gracelessly from an ice cube to totally freeze-dried. I resign myself to "when in doubt, water a little." Everyone has to sort of suss out the balance to strike in their climate... there is a long-standing tradition of piling snow on one's troughs.
