Is too much oil in the crankcase a problem?

5 quarts of oil were put into my 2004 Miata.  On the dipstick, it comes up  a
bigger distance than the distance from "low" to "full."   The old oil was
drained thoroughly.

1.  Will this overfill hurt my engine?   I'm not driving it again until I find out.
2.  Is the oil pan or dipstick or something an odd shape that causes the
high dipstick reading, or does the dipstick reading mean I'm over a quart
full?
3.  How much oil is missing at the "low" dipstick mark?   Thanks!