There are many terms for a given problem as well as a system of equations for all of the interactions. The answers for even 3 body gravitational problems are chaotic, and gravity is less complication than schrodinger.
However, using numerical methods, symmetry, and observation we can model how many-electron atoms behave.
Here is an exampleexample of how the mechanics of a helium atom is determined: http://www.physics.usyd.edu.au/~oliver/PHYS3060/Lectures/PHYS3060-QM11-Handout.pdf.
Quantum numbers arise as discrete parameters for solutions to the schrodinger equation as well as being observable. The Pauli exclusion principle is empirically found. We combine concepts together to model a larger atom, and then further to model molecules (Molecular orbital theory).
The Schrodinger equation works well, but it isn't the whole story.