Oh my, what a busy boy you have been! (Or is that "asininely assiduous"?)
I think a steradian would have flat sides, more like a pyramid than a cone, but really, who cares?
I refer to lumens as a rough guess of how "bright" a light will be, but for me the best info is gained by just turning the damn thing on! Units of light like candles, candelas, lux, lumens, foot-candles, etc. are too esoteric to be of practical benefit to me; attempts to provide a "scientific" precision to a natural phenomenon (human vision) that is too subjective to be quantified scientifically.