I understand you've had the experience of 'Oneness'(for lack of a better way of expressing it), and are able to identify with all things. What does the contemplation of neti-neti look like for someone that's not able to relate? Is the cat I? Am I the chair? We share molecules. Is that the same?
(Not trying to be difficult, this has always been hard for me to grasp.)
I don't think for a minute you're trying to be difficult.
Neti-neti isn't about identifying as that which appears to you, but rather a Self-inquiry that involves a process of negation. It translates to "not this - not this."
In essence, worldly things one would commonly identify with are negated one by one until all that remains is the Atman (Self). Essentially, anything that one observes is negated as the Anatman (not Self), things such as the physical body, one's breathing, one's senses, one's sense organs, one's thoughts, and so on. One continues to negate each item one can observe and when nothing else can be negated, that verily is the Atman.
Emotions can come out of nowhere at times, and aren't always controlled. Its hard to step in poop and not get disgusted, or to get punched and not have either fear or anger come up.
Absolutely, and in the process of neti-neti, the identification with the emotions is negated. It's an object that is observed, but not part of the Self. It is a temporary appearance but needn't be touched. One needn't attach oneself to such emotions.
I stepped in poop. It happened; disgust won't reverse what happened or clean the poop of my good white boots. I realize disgust only hurts me and leads to suffering, so I'll just acknowledge what happened, clean off my boots, and the temporary appearance of poop on my boots no longer exists. As far as getting punched, the pain will be temporary. Anger or fear will only result in my own suffering, so I choose to not be attached to either of those, accept the temporary appearance of pain is what it is, remain mindful that another punch could coming, and focus on avoiding it. This ties to the two arrows in Buddhism I've posted many time on the forum.
Do you think gratitude in general helps curb negative emotions regarding actions(either performed, or performed on you)?
I do. This is something I've been working with my daughter on. Whenever a negative emotion comes from an action, think of something related to that action or resulting from that action that you can be grateful for, as in the dishes example I provided above.