Linecaps on zero-length subpaths

I have a few questions about the drawing of linecaps on zero-length subpaths

According to http://www.w3.org/TR/SVG/painting.html#StrokeProperties, any
zero length subpath that does not contain only a moveto should have
linecaps drawn.
However http://www.w3.org/TR/SVG/implnote.html#ArcOutOfRangeParameters says
that a zero length arc segment (e.g. with identical endpoints) should be
omitted entirely.

So what I would like to have clearified:
1) Should a subpath consisting out of a moveto and a zero-length arc
segment (d="m50,50 a10,10 0 0,0 0,0") be stroked?

2) Is it true that for a closed subpath with zero length, the
directionality at the start and end point is aligned with the positive
x-axis in user space?

3) Is it true that for the first segment of an open zero-length subpath the
directionality of the start point is determined by
the moveto before this subpath (for the moment assuming that it does have a
direction)?

4) Is it true that for the last segment of an open zero-length subpath the
directionality of the end point is determined by the moveto after this
subpath (for the moment assuming that it does have a direction)?

If 3 and 4 are true, and when stroke-linecap is set to square, what will be
drawn may not be squares because the linecaps can have a different angle
from each other (d="m50,50 m50,50 a10,10 0 0,0 0,0 m50,-50"). Also, a
linejoin should now be drawn between them.

Regards,
Paul Dicker