Answering your question takes thirty pages of my 208 page "LightWorks in Archicad" book. If you order from me today, it will ship from Sydney tomorrow.
Here's a summary:
I agree that the lighting controls in Archicad 9 are confusing. That's why I saw an opportunity to write a book and tour the world giving seminars.
To make a soft, well-exposed scene, you need four light sources: Sun Object, Sky Object, Undersun Object and Ambient light to perk up the inevitable, murky shadows.
The undersun, made from a Sun Object set to -90 degree altitude, comes at the building from below the ground shining upward because you turn shadows OFF.
You can soften the light from a Sun Object by wildly increasing divergence.
Camera light OFF. Always, except if you want highlites in chrome furniture.
To enable THESE lights only, turn off the SUN in Photorendering Settings. Enable LAMPS only. Ignore internal shader SUN.
Internal renderings require a different approach.
Another twenty pages. For interiors, I also share a technique using the built-in SUN and three general lights to plausibly fake radiosity in just seconds.
Good luck.
Dwight Atkinson