Working backwards:
if I use Qimage to sharpen the image at 100% view, can i then save it, and if so, does it overwrite the original image file or create a copy ?
The answer is no, if you want or no
When using the batch filter screen for adjustments like USM, on leaving the screen, you are asked whether you want to "associate" the filter or create a new image. When you associate, a separate filter file is stored in the image folder and applied every time the image is opened to view or printed, i.e. is a "non-destructive" system.
You can "save as" from the filter screen too.
would a detailed landscape image typically require a smart sharpening setting higher than default (5)?
With smart print sharpening, the basic idea is to find a setting such that your prints match the screen image wrt sharpening and once set, and in most cases, will need no further adjustment.
I think there are some users who may make small changes to the smart sharpening level depending on the subject, but most probably just use the one setting and the default of 5 is a good place to start.
would any users like to post any settings for image sharpening
This depends on how your images are being made, camera jpeg, converted from raw in another program, using Qimage to process and print from the raw file - and your own personal taste.
I generally use the latter method and so have my raw preferences set to 2, 200%, 70% and only add extra USM in a filter now and again depending on the image. A good general rule for extra USM is "less is more"
I'd rather see a under-sharpened image than an over-sharpened one.
I'm sure you'll get plenty more views on this subject
Terry.