I am not exactly sure what you are asking. My guess is that one of the below answers will help:
Admin Posts are not automatically relevant as I have had quite a number that were not. That said two factors make them likely to be relevant in terms of score: 1) we usually only share high quality content 2) many users automatically up vote and stake on anything we share as soon as they see it (I typically have a dozen up votes within 1 min of sharing no matter what time of day).
I do not only or even mostly up vote other Admin’s content. Read through New or Spam, many pieces of content are shared every day. I skim or read most of them. I also up vote the best dozen or so per day and probably down vote a dozen or more as well. I typically leave most articles untouched (no up or down vote).
Posts by non-admin are typically successful if very relevant and nuked if highly irrelevant. The ones in the middle can go either way, but usually end up below the cut score for payout.
Yes, Admins are eligible to vote. When metrics are finally available, you will see that I have probably made tens of thousands of up and down votes. The vast majority of them were not on Admin content.
PS You tagged the wrong person in this post as the “Slava” you tagged is a scam account.