Ignorance As A Point of View - Climate Change

Where a non scientist asks a few questions about climate change.

Consider the planet Venus. Very similar is size, mass and orbital distance from the sun to the earth. Cloaked in “greenhouse gas”, specifically carbon dioxide.  Venus has far more volcanoes than any other planet. However, best guess is they haven’t been active for a 1,000 years.

http://volcano.oregonstate.edu/oldroot/volcanoes/planet_volcano/venus/intro.html

Per this article, very few of these volcanoes are of the eruptive type, such as Mt Merapi, the current Indonesia bad boy.

Because of the dense atmosphere on Venus, there is very little wind (again, per this article).

Next,

(Reuters) - Small volcanic eruptions help explain a hiatus in global warming this century by dimming sunlight and offsetting a rise in emissions of heat-trapping gases to record highs, a study showed on Sunday.

http://www.reuters.com/article/2014/02/23/us-climate-volcanoes-idUSBREA1M0W920140223

So, what happens to all this “stuff” these volcanoes eject into the atmosphere? Doesn’t it get mixed with the rest of the atmosphere by way of wind action? There must be many chemical reactions taking place, perhaps with carbon dioxide and other “green house” gasses, changing them into something else.

I know volcanic ash can stay in the high atmosphere for decades, but doesn’t gravity eventually bring it to Earth? Perhaps this causes a “scrubbing” action in our atmosphere that was weak on Venus as little ash was ejected into the atmosphere. Venus got hot, the Earth stayed habitable.

So, here my lack of scientific knowledge is exposed. My hope is folks who do know and understand this stuff might comment.

Swiped the above picture off Google Images. Given the atmospheric pressure, and relative lack of wind, would these be the type of clouds you would expect?