FFT coefficients question

Question

I\'m a software engineer working on DSP for the first time.

I\'m successfully using an FFT library that produces frequency spectrums. I also understand how the FFT works

Answer 1

1. You are correct. FFT coefficients are the signal values in the frequency domain.
2. "Energy" is the square modulus of the coefficients. The total energy (sum of square modulus of all values) in either time or frequency domain is the same (see Parseval's Theorem).