Did you made any progress on that topic because I have here someone that is starting to work on NN & Sofa and may be interested with what you experienced.
1) Resources for SOFA :
– follow the online documentation
– watch our first Tutorials on YouTube
– start using SOFA, running the examples/Tutorials
– read a reference paper about SOFA
– browse the SOFA API
2) SOFA base modules in my C++ code is fine for your purposes at my best knowledge