[chunky1994]

I think the suggestion of tying the upvote to an endorsement may be a bad idea. It would be conflating the fact that you want the comment to be seen with the possibility that you might agree with it. The comment could be tangential/adversarial to your opinion, and so you might not upvote it, however it could still add to the discussion, and hence you would endorse it.

To answer your second question I believe pg has stated that only users with over 10000 karma have their comments automatically endorsed.

[leephillips]

"The comment could be tangential/adversarial to your opinion, and so you might not upvote it, however it could still add to the discussion, and hence you would endorse it."

I was under the impression that upvoting was to reward comments that added to the discussion, rather than for ones that you happened to agree with. I have upvoted comments that expressed a view that I thought was wrong, and that said that I was wrong, because they were good comments. There is always a chance that I'm wrong, however infinitesimal that might be.

[pigDisgusting]

Sir, your response is well-reasoned and satisfactory.

  "I do not agree with what you have to say, but I'll 
   defend to the death your right to say it." 

  - Voltaire