Ross,
If this were my tree, I would enjoy this year's blooms. In the Charlotte area, on a healthy tree, if I was looking to increase the trees vegetative growth, I would remove all the blooms and ovaries as the blooms begin to fade (the show goes past it's prime) and start looking to eliminate the 3rd, 4th or even 5th new shoots that emerge below the ovaries while I am at it. Try to leave only 2 buds or shoots where you cut the blooms off. Azaleas produce whorled growth like pines, so eliminating some of the emerging whorled branches as you are removing the ovaries will direct the energy to the remaining shoots. Without ovaries, the tree will not waste energy on seed production. This will also increase the amount of vegetative growth you get, and help with more flower production for next year as well. If you want to decrease the number of flowers produced next year to continue to focus the tree on vegetative growth, do so this summer as the tree starts forming flower buds, rather than in the late winter/early spring after the energy has already been spent.
Be mindful that azalea are basal dominant; the strongest growth is at the base of the tree, and the weakest shoots are at the top of the tree. Keep more foliage on the top to keep it vigorous, you can cut the basal shoots back harder than on apical dominant plants like elm or maple.
I use 50% regular bonsai soil and 50% kanuma with my azaleas in the Charlotte area. Other bonsai folk around here use 100% kanuma and like it. They tend to have sunnier yards than mine. Some don't use kanuma at all. Stick with what you are using if it works for you.
Regards,
Martin