Great write-up, I enjoyed reading it and agree with your general remarks and bullet points. Especially your note about ignoring impermanence by saying "Yeah, I know what impermanence is."
-If what I put forth is valid, do other key realizations follow any of the same criteria that I noted in my 6 - 7 items above? For example: are key realizations generally right infront of us but remain unseen? Are they often missed because we think we know them already, etc?
Yes, generally. As we are only toying with perception, perception is not something that can be observed while also in cessation. In other words, as long as you're perceiving, insights are available to be had at that very moment, always. So if there aren't insights happening, it is because perception is not being entirely understood at that moment. This may mean we don't know where to look, or how to look, or we're avoiding looking, or think we know something we don't and thus ignore what we needs to be looking at.
-Currently I experience a&p in terms of sensations, but as yet I do not experience things in terms of "vibrations" like I keep hearing about it Daniel's book. What is he talking about exactly?
There are several old threads you may be able to dig up by searching for them. They exhaustively talk about this.
-As per the "noting" process of a&p that Daniel speaks so highly about in his book; he strongly recommends giving names to a&p phenomena at a rate 5 per second. Is this practice as litteral as it sounds?
You generally want to note as quickly and "widely" as you possibly can, given that you are still accurately perceiving of each sensation as a distinct sensation. Thus, 5 per sec may seem fast or slow, but you're really just shooting for as many as possible. They quickly become uncountable, like reality is a TV screen with white noise on it. It is also important to note that speed is also not always what you're going for, and that the breadth of the sensations you're noting is sometimes much more important. In example, let's say you're in 4th Vipassana jhana, Equanimity. You may be noting what seems like 100 sensations a second everywhere you can find, but if you're missing a sensation such as peace, or spaciousness, then you may stagnate. The point is that the actual sensations being noted does matter in certain cases.
Further, as things speed up, you don't need to verbally note.Thus, you don't have to disrupt your "no thought" approach, though it is worth mentioning that thoughts are, in the buddhist sense of the term, not a problem. And thus, verbal notes are also note a problem, because, as you say, they are also just empty phenomena arising and passing away.
-Experiencially a&p feels as if ALL things are born and destroyed, yet the Heart Sutra says all things are "not born, not distroyed", why?
I believe that line of the sutra is capitalizing on the "untouchable, all encompassing aspect of Awareness," as seems common in Mahayana and Vajrayana literature. My personal opinion is that Awareness is a silly twist of one's overactive imagination, and that all things ARE born and destroyed, without any exception, including any perception of Awareness. This will almost assuredly impact your later practice, so I urge you to proceed with care, regardless of what opinion you arrive at.
Best,
Trent