"it sometimes returns TWO numbers..? "
Unlikely. Try to assign the return value to an int variable and see what you've got in it.
"and what are the "Min Max Values" shown in the AEd..? (0.000 / 93.000)? "
Min Max represents the range of the curve u parameter. Think of it as a continuous numeric range that represent all points on curve. So min is starting point, max is ending point and say 46.3 (in your example) is somewhere in the middle of the curve.
This is very important in modeling since operations such as stitch or attach depend on correct parametrisation of input surfaces which again depend on parametrisation of curves.
You can use Rebuild curve command to change the parametrisation. There ara two common parametrisation models; (1) arc len and (2) number of spans.
When curve is parametrised by arc lenght then parameter ( most common in range 0-1 ) represents the percentage of the curve length. point with u = 0.25 is exactly at 1/4 of the total curve length.
When parametrised by spans then each span length adds 1 to curve parameter. For example point with u = 3.5 is exactly at the half of the 4'th span.
Try to select some curve points and maya will show the parameter on the status line.
You can also use Create->Measure tool->Arc length tool to attach the parameter locator to a curve.