you probably don't have the HVAC module but have you checked the halogen lamp tutorial? there is some good information in there.
also, have you considered a flow simulation training class to augment your sim knowledge? in addition to that, at hawk ridge systems my team offers one-on-one training on specific problems like the one that you have. basically we walk you through setting up your problem, all the assumptions..etc. essentially what you're asking for.
but to answer your questions more generally.
environmental radiation = radiation from your component to an "environment" far far away. i would recommend having this on as it happens in almost every situation.
don't play around with radiative surfaces at first. start with black body and then tune the surfaces based on finish and color afterwards.
radiative sources, don't worry about that at first.
the other question you'll probably want to ask yourself is if you want to run this as an internal or external analysis.