min and max extrusion width?

So I have a Solidoodle4 with a 0.4mm nozzle.

All I know is it can print at 0.31mm for support material, which is the default slicer setting from the official download.

But how low can I go and how high?

Something like 0.2 or even 0.1mm for outer perimeters for some objects would be really cool.
And 0.5 or 0.6 for infill would be cool too.

Those two examples are what Slic3r website suggests this feature of different diameter for outer perimeters could be useful for.

But in practice, how low and how high can (should) you go?
I wouldn't want clogs or some similar bad thing happening for my lack of knowledge.

.1 is probably a good low. And you can't go higher than .4, with .3 being probably the max.

I go with 25% as a minimum and 75% as maximum (if you ever change nozzle size), so I concur with the 0.1mm being your smallest and 0.3mm being the widest you'd want to go before loosing surface quality.