question is ... when you do get good at equalization and get down to
like 30 feet or 40 feet or something, what happens if you accidentally
let your ears "pop".

That is the whole idea. You should think of yourself as a sponge where
the inside pressure is equal to the outside pressure. Hence the term
"equalizing your ears." You may have to use two fingers to pinch
your nose closed and blow to force air into the area to equal the water
pressure pushing against your ear drum. Equalizing... do it early and
do it often. Once you get past the first atmosphere it gets easier.

what i mean is, i understand that you have to
force air into your ears to keep from experiencing pain. sort of like
positive pressure inside. but what happens if you accidentally swallow
and all that pressure goes back into your throat, doesn't it go back to
the same pressure it was at the surface, won't it suddenly be like you
had never equalized at all ? or does it just let the ballooned air out
enough to be equalized with whatever depth you are at ?

Go to a used bookstore and buy an old 10 buck SCUBA book. Your
questions suggest a need for some basic diving physics and physiology.
Besides, if your not sure of the "forces" that govern humans under
pressure you may be better served paddling on the surface.

Read and learn.... and then enjoy the water. You'll have a much
better and safer time armed with some information.