Does suffering entail being overwhelmed for the person who is suffering? Also are there behaviors that all humans do when they suffer? For instance, do all humans try to alleviate suffering when they experience it?
-- "Does suffering entail being overwhelmed"

Yes, I think it often does...

...In some cases, when a disagreeable experience arises (irrespective of its sensory modality) we have a strong and completely unconscious attachment - and so suffering arises immediately and without any resistance. In this case we can't speak about "overwhelming" (or else we could categorize this as an absolute "overwhelming" that meets zero resistance) This probably happens more often to children and to people with relatively undeveloped Emotional Intelligence...

-- But in most cases, modern people have developed various coping techniques to try and alleviate potentially disagreeable experience and prevent it from turning into suffering.

The main technique I see people using every day, many times a day, is "reinterpretation". This is when a person re-frames a (potentially) disagreeable experience to make it agreeable. For example, someone drives to a supermarket and sees all parking spots near the entrance taken. The spots in the middle of the lot are taken too. The only available spots are on the far end of the parking lot. The person then re-frames the experience by saying (out loud or to oneself): "This is even better. Will make me walk a longer distance, and I can use some exercise."

Most healthy people have very "healthy" but also rather unconscious habit of re-framing everything they encounter as to protect their inner comfort. They re-frame circumstances, objects, people, and events in such a way as to reduce a sense of failure, doom, inadequacy - and ensure inner peace. Because we are intelligent species, many of us (but not all) prefer these re-interpretations to be logically consistent and to add up to some sort of more-or-less cohesive life philosophy. This requirement of logical consistency makes this process exhibit a kind of self-sustaining growth, what I call hardening of the ego. What I mean by that is the fact that for most people, their newly made (re-)interpretations arise from -- and add to -- the existing set of internalized interpretations. In other words, the new interpretations are offered by the ego to ensure its integrity. If a new re-interpretation successfully manages to prevent a disagreeable experience from turning into suffering, and does not meet too much rejection from the external world, it is added to the ego's collection of workable interpretations. Thereby tightening up ego's space of possible interpretations, or "hardening the ego".

For example, if someone's life grew out of a difficult background, and he or she was not taught positive re-interpretation, this person's ego starts framing the difficulties as something normal and expected, using this as its coping mechanism -- suffering getting reduced when experience match expectations. This interpretative style continues to accumulate new interpretations until it hardens into a cohesively negative or pessimistic worldview. Other people harden into an optimist, a villain, a victim - with corresponding worldview to match.

Most people who grow up in a consistent and non-conflicted environment, by the time they reach adulthood end up having a virtually impenetrable ego with no possibility of interpretative ambiguity - and therefore no space for maneuver when a re-interpretation is required to alleviate another piece of disagreeable experience - but no logically consistent interpretation can be offered without breaking the logical network of assertions comprising the ego. When this happens, we end up being helpless in the face of the disagreeable experience, which at that time can be said to "overwhelm" us and arise as full-blown suffering.

As Buddhism developed historically, it developed various techniques for dealing with this entire pattern of suffering, its arising and prevention. These techniques range from primitive, such as simply "enduring"; switching attention; and forcing the thoughts out, to re-framing, such as seeing things "phenomenologically" as mere "stimuli", "notions", "feelings", "energies" etc; to detachment or letting go of deep-lying assumptions&amp;preconceptions that lead to evaluation of experiences as something negative, to methodical deconstruction of ego's existing interpretations, to non-evaluating acceptance of all experiences, and finally to interpretative ambiguity.

What's cool about interpretative ambiguity is that it ends up being rather enduring in the face of disagreeable experiences of all kinds. The complete mastery of interpretative ambiguity prevents any possibility of being overwhelmed with a disagreeable interpretation of any and all experience. In other words, it prevents suffering.