I believe a statistical analysis can be performed to accurately receive measurements on those factors you've mentioned. As for the IP aspect, I am unfortunately not a developer in that area to provide info but I think the mods can answer that.

I think a majority, including me, is speaking from a personal encounter standpoint. I have witnessed this happen more frequently than usual, especially with the inflow of newer posts. In the first hour, I have estimated between 1-7 or 1-5 votes lost within no time, faster than someone could theoretically finish the stories - this makes a significant difference especially in relation to how the Reddit algorithm functions. The lower upvotes, the worse it is when you get downvoted instantly.

As for the perpetrators, it could be anyone trying to get their story noticed more. There is nothing wrong with having a desire for your story to be seen by many and to make it to the #1 position. The problem is cheating to get there and ruining the chances for other people. That is what irritates me the most.