Answer 1

It is up to you, what language to choose. It can be C++, Java, Python... Each of them has modules/libraries for math calculations if you need calculate voltage, resistance or other parameters. Also there are graphical libs for visualisation if you need to draw electric schemes. It depends on your task.
C++ will be the best option, but it requires base concepts of programming and working with memory. C++ has best performance and many opportunities.