http://members.cox.net/spambait/FSXTweakGuide.pdf
I've only scanned through it, but what I've seen, it gives details on tweaking (which has been covered in this forum) as well as determing how to set your sliders, right at your fingertips. For the most part, I've been cutting and pasting various threads about tweaking fsx.cfg and putting it into a file called FSX Documents.
Hope this helps.