Please note that the article you reference is over three years old. A more current discussion on this topic can be found in this forum, by clicking this link . (And even this was posted before the release of Version 4.40, which addresses this "Code" change.)

CAESAR II follows the current code. This means that it is assumed that your tee doesn't meet the dimensional requirements, and you end up with a higher SIF. If you do meet the dimensional requirements, then you can flip the configuration switch and have CAESAR II compute the lower SIF (which is what all prior versions of CAESAR II assumed).

The other way to obtain the lower SIF values is to specify the two dimensions on the dialog. If these values meet the requirements of Appendix D,
CAESAR II will automatically compute the lower SIF.

As to your last two questions, I'm not in a position to offer advice here.