1. Nameplates vibrate sometimes. Probably due to move nameplates to feet option. Doesn't always happen, but enough to be annoying. When it does happen, panning your camera in any direction will not get rid of it. Even dragging your camera all the way down it still does it. So it doesn't just happen at the threshold where the nameplate are supposed to go to the feet.
   Video: http://www.twitch.tv/redward_tv/c/6973656
2. Health bar eats right click action and prevents camera movement as a result. Even when you disable health bars (I do for friendlies), it still eats the right click where the health bar is supposed to be. Pretty frustrating in larger group content or open world events where there are a lot of people and I can't pan my camera.

1. I know about this and seen it few times but I'm not able to replicate it to see whats causes it.
2. You can disable this in options. Just uncheck 'Clickable nameplates' under the general tab.

Can you make clickable nameplates work with just left click and not right click?

I think its possible, but I'm not sure. If stock nameplates support it than it's possible for sure.

Since there's an eMouseButton parameter passed on the MouseButtonDown event, I imagine you can use this to filter on a certain mouse button, if desired.

OptiPlates does it. I believe Carbine ones do too? Haven't used those in ages though.