Re: Twin camera Overlapping/Staggering
What were the alignment parameters, perspective, rotation, et al?. And most interesting: did you find a difference between the focal lengths of the images?
Unfortunately, I worked on temporary folder and did not keep the project.
From memory, the yaw was about 20° and there was a small roll (less than 2°). I do not remember if I enabled pitch optimization, probably at least for one side. The difference between focal lengths was quite small, but needed to be corrected to get a good alignment (I used the Z field to correct it, I think it modifies the scale - more like 98% than your 85.5%)
I already got hugin find a solution with weird scale results for other images liked stmani did with this one. I think I tried to start from other initial conditions in these cases.
The monkey is Suzanne, the blender's test model, which can be added to a scene with a few clicks (and a few others for texturing it).
I find blender useful to check some assumptions as the cameras can easily be placed in a controlled position.
I also used it for some stereoscopic images, some of which I published on stereopix, including a few completely made with this tool. (other users did it: https://www.google.com/search?q=blender+site%3Astereopix.net)
The software is so powerful that it is vain to try to master it completely. It is better to learn the parts that you need when you need them, and there are tons of resources for it. I know only a very small portion myself, but it allows to do some interesting things.
I saw a BIG improvement for beginners since version 2.80, and they also released a nice series of videos presenting the fundamentals:
Though, using it still requires an initial investment of time.
I do not know.
Lets say that the 24mm EFL is used and that the crop is made so that it is equivalent to what a parallel rig would do, the EFL (with 18.4° angle) becomes 54mm (horizontal; vertical FOV is bigger), not hugely high.
So the question becomes: is it better to have a smaller base with a crop factor that limits the wide FOVs, or a larger base with which you will have to shoot from farther away.
I guess that the answer depends on the composition you want. (and perhaps also on the final definition you would like)