What criteria does the Academy uses to give a statuette in the Scientific awards and why it was decided to have a separate ceremony for them? [closed]

I always wanted to ask this question since the information that I could find didn't really cleared my doubts in the subject. This arises from the fact that my favorite awards aren't telecasted and the only way to know the winners is through Oscar's site.

Okay, I'd like to separate this question in two parts:

The first part is what is mentioned in the opening sentence of my question. I've read the Wikipedia entry on the subject and clearly explains that there are Three kinds of Scientific and Technical Awards:

One which is the Academy Award of Merit (an Academy statuette); there is also the Scientific and Engineering Award an Academy bronze tablet; and a Technical Achievement Award which is an Academy certificate.

This part I got it clear. But upon reading the article it doesn't explain much on what elements exactly this innovation must have so that the Academy decides if it is worthy of any of such awards or which innovation deserves a higher recognition than other. In other words a decision factor which makes the innovation worthy of an statuette, a bronze table or a certificate. Does it mean that this is subjective to a panel of experts?.

Upon looking at the recipients of the statuette it seems that with the years the academy has moved from giving the award to analog imaging techniques to computer generated imagery and digital recording techniques in both audio and video, which doesn't surprise as they are innovations which came to be developed from late 70s (although rudimentary). Although in the list there is stated the reason why that specific innovation was worthy of the statuette it doesn't really mentions the criteria that is currently demanded in today's interest of the academy for innovations in the industry. Let's say for the 2012 Awards they awarded continuing innovation in the design and development of the ARRILASER film recorder, but on the following year they given the statuette (not sure if it was symbolic) to all those who built and operated film laboratories, "for over a century of service to the motion picture industry. In the end this seemed to be more like an honorary Oscar than a technical award. Because of this reason I asked this question.

The second part of my question refers to what was the decision for the exclusion of the Scientific and Technical awards from the Telecast?. By reading the explanation given in Oscar's site they only mention that the award was part of the ceremony (and I presume telecasted) until well into the 70s. But as of today, we only see just bits of the awards in a short clip during the show if they decide to include it. This year as the ceremony was shortened was omitted much to my dissatisfaction. But what was the reason, and I'm not referring to present time but on why it was decided to make a separate ceremony for those awards. Was due time? Due unnecessary coverage? Due ratings?.

Finally, although it is explained in the Oscar's site that John Bonner's award is not necessarily given every year. It doesn't say the same for the Gordon E Sawyer awards. Does it exist a reason why to award the price in a year or to skip it all together?.

Maybe I have over extended with this, but as I mentioned I couldn't find more reasons than what it is already known. So if someone has more expertise on this I'd really appreciate you could include this in your answer with some reference.