I like a sweeter smoke as well. I do 4 to 1 dark brown sugar to salt mix (along with fine ground black pepper and garlic powder) and I fill my drip pan with straight apple juice.
To prep the fillets I just cut the meat down to (but not through) the skin in 1/2" strips. If you using a dry brine, just pack the slits with the brine - if using a wet brine, it'll get in there itself.
I also learned from a chef to mix 2 parts honey with 1 part water and baste the fish every 30 minutes while smoking.