Many species of cactus are somewhat erratic bloomers, they bloom when they feel like it and sometimes take a year (or several) off between blooming periods. The grey color at the bottom is normal, it's just older stems that the plant is no longer using for photosynthesis. It's sort of analogous to a tree trunk at this point, mostly structural support for the rest of the plant.
Fertilizer is more likely to kill your cactus than help it, they are adapted to a low nutrient environment. Unless you live in an extremely dry climate, I'd say the same thing about watering.
Other than that, I agree with Lori, the red buds are fruits and trimming the cactus probably won't be beneficial.
