Fertilize both just after they finish blooming in the spring. Anne's choice of fertilizer is one of the organic products such as Espoma.
My heroes! Long time listener - thanks!
Trim them back at the time you fertilize them to the desired shape. also, be sure to hand water the grannular fertilizer so it will penetrate the mulch and work it's way to the roots.
For azaleas, you can fertilize in the spring or in the fall. If you've had it a long time and it hasn't died... it probably gets sufficient food from it's surroundings, like under a pine or cedar.
They love having an acidic soil. I'd say a fertilizer that's granular and is a slow-releasing type would be OK.
Regarding Camellias... don't know.