Hello Gregory,
You should better have posted your topic in the dedicated GAIA / SISYPHE section rather than in TELEMAC-2D as your questions deal with sediment transport and SISYPHE rather than hydrodynamics and TELEMAC-2D.
I think you would get more answers over there. I have just moved your topic in the right section.
Anyway, if you use Linux, you can use a command like grep to find the caller graph.
Another way is to use doxygen and its search
docs.opentelemac.org/doxydocs/v8p2r0/html/index.html by typing init_compo.
You then get e.g.:
docs.opentelemac.org/doxydocs/v8p2r0/html/index.html
and the caller graph below (expand the array).
It is linked to releease v8p2r0 but it is quite the same for v8p4r0 I think for SISYPHE.
For the other questions, I let more experienced users answer you.
Hope this helps,
Chi-Tuan