Hi,

(1)Statistically, which of these two is MOST
LIKELY the cause:
The function-switch or the element?

Element.

(2)Is there a third possibility? (e.g. are there
an 'fuse-like' things that are designed to burn-
out/switch off in the lower-element circuit that
could instead be the problem?)

Burnt wire, fuse is possible but normally would effect the broil as
well, clock set on auto instead of manual ( not all ranges ),
thermostat, selector switch, etc.

How to ohm test an element...
http://www.applianceaid.com/elecrange.html#element

How to change ( if needed ) a common bake element...
http://www.applianceaid.com/elecrange.html#change-bake

jeff.
Appliance Repair Aid
http://www.applianceaid.com/