as posted by @afischer in this post , there are indeed some shortcuts that you can use.
Feel free to add your vote there to increase priority for this feature.
“r”: Reset the view to the original view point before being adjusted to the current geometry
“a”: Reset the view to fit all objects (default view)
“u”: Changes to an upright view of the current scene
Additionally “w”, “f” and “l” trigger different navigation modes which are sometimes nice to play around but not very helpful when you work with the viewer e.g. select / hide entities etc. We might disable them in the future. You can get back to the default mode by hitting “e”.
Regarding your questions:
Double-clicking on the model will change the center of rotation of the model to the location of the clicking point.
Ctrl+Left Key = Pan
Let me know if that helps and if you have some ideas for improvements.