Re: Upvoting self?
I think I have got this right... but will check with my technical superior.
Our voting UI is not joined at the seams. IIRC you can't actually upvote or downvote yourself - it only looks like you can do this.
Likewise with multiple ups or downs on the same comment. Our system only records the commentard's latest vote - i.e. it expunges the earlier vote. Again this is opaque.