okay then, while the main tutorial on camera, rendering, lighting, atmosphere and backgrounds (say: the Empty Scene) can be expected say end of this month, some notes on the settings presented above. As I'm not The Big Wizard but just finding out things myself, please comment, preferably with the appropriate (documented) arguments.

Max Bounces: tells Poser to kill the light rays which have not lost all their energie yet and still can make it to the final result. Meant for test renders in reflection / refraction intensive scenes, and can cause artifacts. Nature does not put a max to bounces, and reduced values affect IDL lighting levels especially in indoor cases. In my final renders I put it to the max.

Irradiance Caching: a trick on not sampling all relevant spots for AO or IDL, but just the percentage you enter (values are 0..100%). The rest is interpolated, causing inaccuracies, so this is for draft renders with AO or IDL. Note that the various Auto-modes present values from 60 up, Poser seems to disadvice values under 50.
As the sampling / interpolation brings in some overhead, you're better off switching it OFF instead of using values over 90.

IDL Quality: again a percentage 0..100% of something, its about the amount / density of rays used in the IDL calculations. Outdoor scenes seem to do fine with values over 80, indoor scenes might require values over 90, while values over 95 hardly contrbute to a better result but do require far longer render times.

Filter: when you're antialiasing the result, you might want to re-sharpen the textures on the objects. Filter does so, like AA, at the subpixel level which makes a difference from sharpening the final result in post. Value 1 means: no filter, value 4 means: extreme filtered (disadviced). Value 2 means soft filtering, nice for female skin, outdoor clothes and organic textures. Value 3 means hard filtering, nice for male skin, short animal fur, and details on indoor clothing. SYNC then is the best mechanism for the required sharpening.

Bucket size: note that it's a max value, Poser will reduce the bucket size dynamically when resources are at stake. Bucket rendering comes with overhead, because they're rendered with an edge: 32x32 renders as 48x48 while 64x64 renders as 80x80 (8 bit edge all around). So smaller buckets have more overhead, therefore halving bucket size will not reduce memory requirements to 25% but to 35%, while rendertime will go up to say 145%.
On the other hand, when buckets become too large, there will be no new buckets to start at the end of the rendering process, CPU threads will run idle and you'll have to wait till the last bucket is done. No speed gain then.

Whether smaller buckets really solve the "hot render spot" issue depends on whether that spot can be smeared over multiple buckets. If it really is a spot, that won't be the case. In my experience it paid off to investigate on the causes of it: did I switch off Light Emitter for hair? Did I disable real reflections for teeth (specularity is good enough)?

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Usually I'm wrong. But to be effective and efficient, I don't need to be correct or accurate.

visit www.aRtBeeWeb.nl (works) or Missing Manuals (tutorials & reviews) - both need an update though