Making sense ot the 3D View and aligning and rotating objects by specific values I am trying to line up a camera and a mesh in the 3D viewport.  I am having LOTS of problems.
a) I have a green line - I assume this is the X axis, though it is not labelled, same for the blue line. How do I see all three axes?
b) I set the cursor to world origin and then set my mesh to cursor, but the mesh seems to just go wherever it wants to go - and certainly not to the cursor.
c) is there a trick to navigate around the 3D space without it turning upside down or moving in an unpredictable manner?  How can I even tell if it has turned upside down?  Is there any way to move the view in a single axis at a time?  I am just usinhg my Mac trackpad with 2 fingers but it drives me crazy.
d) after selecting object I noted that the Y scale was slightly different - setting it back to 1 (same as X and Z scale caused the model to disappear altogether - I never found it again...
e) I thought that having a collection including lamp and camera might be causing Blender to snap the collection rather than just the mesh - but I moved the mesh out of the collection and it made no difference.
Really, this is driving me nuts!
f) Setting the mesh origin to cursor evidently does not move the mesh to the cursor - so how do I move the mesh itself so that it is sitting EXACTLY on all three axes?
dI solved this issue by selecting the camera and moving it to the cursor at world origin.  Then with the camera view open in another window I was able to move the camera along the X and Y axes until the model came into view (upside down!) and then rotate the camera until the model was the right way up - using the rotation properties box to specify the exact rotations - 90 / 180 / 180.
The Y axis alignment was done by eye - I could not find any way to centre the camera exactly on the centre of the model.
It will have to do...