I haven't found a reason to only cast starsurge when it procs because it has such a long CD, so always keep it on CD by spamming the keybind. When Shooting Stars procs you'll get the instant.

I use Jamba to tell me when an eclipse procs and switch between wrath/starfire then. Its true they never really all eclipse at the same time, but switching all of them at once keeps them fairly close, just a couple seconds difference.

Mastery increases damage from eclipse and since boxing I am not perfect on the eclipse I just stack crit and reforge out of mastery. I only really use 3 dps keys for my boomkins and 2 support keys, using IsBoxer I just send 1-5 to every toon and have decent dps for my iLevel compared to others in LFD.