The focus is managed automatically before each observation (autofocus). If you feel your picture is blurry or out of focus, you can manually ask Vespera to start autofocus through the observation screen.
Yes. Tiff files for manual image processing are generated from the automatically calibrated images (if the feature was enabled before the observation).
You can find a detailed tutorial on this link about image processing for the three different image formats used by Vespera. The tutorial includes recommendations on which software to use based on the selected image format and your level of expertise ...
No. The Universal Master Dark uses specific algorithms developed by Vaonis that are not implemented in traditional astrophotography software. For manual stacking, use expert mode to capture traditional darks.