How do I use series and parallel combinations of inductors and resistors to achieve a certain resistance+inductance?
Your test load is not the same as the "real" load, as the comments pointed out. If you ran CircuitLab simulations you'd see that the real load's impedance increases without limit as the frequency increases, while the test load impedance only goes to 5.71 ohms.  Both look like 5 ohms at DC. You should be able to get those results with simple mental checks.

It sounds like you're being too fussy in trying to exactly match the loads, but that depends on what you're trying to do. It would make more sense to test with some kind of worst-case load.

BTW, lower case omega represents the angular frequency which is 2 pi times the frequency in Hertz. Your "real" load impedance at 100 Hz is 5 + j12.56 ohms.

Mutual inductance is unlikely to be a problem, but it depends on what inductors you're using, what you're trying to do, and how close you'd like to pack them.