Compost is pretty hot stuff for seedlings and I'd advise you to get them out of it if it's not too late as they'll most likely burn if allowed to stay where they're at...especially if you start adding ferts any time soon.
SuperThrive is good stuff but is not needed on seedlings unless you're transplanting them and will get expensive if used every time you water. Use an additive such as SuperNova to keep the trace elements up in your soil and other hormones/vitamins instead of the ST. It's much more beneficial for a plant that is otherwise healthy and not being moved any time soon.

Also, seeds do not need light until they break the surface...only warmth. And using a 400W is a bit of an overkill for seedlings and harder on the electric bill. I'd use flouro's while in the seedling stage...