I think your best bet is most likely Celestia (it's free, and it's awesome -- http://www.shatters.net/celestia/). What it does is allow you to create a custom star system with the variables you mention, plus a few others, and then models it for you so that you can see exactly what it looks like. You can find some great tutorials at http://www.celestiamotherlode.net/ca...mentation.html -- I'd start with the Introduction to Celestia Add-ons by Selden Ball, Jr. It goes through the process of creating a fictional star system. From there you'll know which tuts to look for.
As for whether you're mad to consider this level of detail: I've done it, so if you're mad so am I! Also consider that (arguably) what made Tolkien great was the insane amount of detail he put into his fictional world. So as far as I'm concerned, you're making it better with each detail.