1) As I posted somewhere here before, it is impossible to move floating windows to another monitor in a multiple monitor setup if the second (or third or forth or fifth or whatever) monitor is positioned above or below the main monitor (or diagonally up or down, for that matter). Left and right work fine but not up or down.
This is a limitation of the current PixInsight GUI architecture. The only supported multiple monitor configuration is a single row of monitors. A 'matrix' monitor configuration (i.e. multiple rows) is not supported.
This is clearly not standard Windows behavior
PixInsight is not a Windows application. It is platform-agnostic by design.
2) PI does not store floating window positions, you have to drag these each time.
All positions are always stored, but floating window positions are only restored correctly on single-monitor configurations. It's true that there are some problems with multiple monitors. This should not happen, and will be fixed in a future version. It isn't a high-priority task though.
In fact, what would be even better would to be able to drag images being processed to other monitors as well.
Image windows are not top-level windows, but child windows of a workspace, which in turn is a child control of PixInsight's main window (it's actually much more complex than this, but this simplification describes the layout from a high-level perspective). Since they are child windows, you cannot move them outside the main window. This is known as MDI (multiple document interface) design in the programming jargon.
Overcoming these limitations would require a complete redesign/refactoring of the whole platform, which is a huge task. For example, top-level image windows would be perfectly possible (a la GIMP's classic way for example), but such a drastic change would pervade a large portion of the platform, including critical parts of the current module and scripting APIs. Other changes are less pervasive, but would require a lot of work. We are speaking of PixInsight 2.0, actually. But we have many priorities before even thinking seriously on that.
Anyway, IMHO these limitations are of little practical importance. It's a matter of organization. We regularly perform extremely complex image processing and development tasks with single and dual monitor configurations without any problem. Your mileage may vary, of course.
