Creating spherical panoramas with Stitching Detailed

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I have wide angle lens with very low distortion and a tripod.

I would like to create a spherical panorama (360 degrees on the horizontal axis and 180 degrees on the vertical) by using the Stitching Detailed sample (OpenCV 2.4.9): (https://github.com/Itseez/opencv/blob/master/samples/cpp/stitching_detailed.cpp).

I have 3 questions. Here they are:

1) Pictures are always adjacent. Therefore, if I have

1. first.jpg
2. second.jpg
3. third.jpg

I call the executable by typing:

stitching_detailed first.jpg second.jpg third.jpg

The overlapping region between first.jpg and second.jpg is the left border of first.jpg and the right border of second.jpg; the overlapping region between second.jpg and third.jpg is the left border of second.jpg and the right border of third.jpg and so on...

How can I improve the stitching_detailed code both from the "time needed" and "quality" point of view by using this knowledge?

2) I plan to stitch first vertically and then horizontally. When stitching vertically, I use the "--warp plane" option and then, once I removed the black part, I stitch the respective results horizontally with the "--warp spherical" option. Does anybody have suggestions about how improving this approach (or additional options)?

3) When taking pictures from a corner of a room, for example, the stitching becomes more difficult, because of course the FOV is more limited when the the camera is faced to the wall, and the algorithm doesn't work anymore... Did anybody encountered this issue?

I realize that all three questions are quite generic, but my hope is that, if answered, they will help many other people who are trying to use this useful OpenCV class at its best!

Thanks.