You asked a lot of questions that you seem to have answered, albeit incorrectly.
Your first question is a bit misleading because not all CO2 goes into the atmosphere. As discussed before, a lot of CO2 goes into the ocean, or is absorbed by pants ect. We now know that the ability for earth to absorb CO2 is much higher than previously though. So, even if we were to double the CO2 emitted, it would not be a 1:1 increase in the amount of CO2 into the atmosphere.
http://phys.org/news/2012-08-earth-absorbing-carbon-dioxide-emissions.html
The way CO2 increases global temps is not strait straightforward. The wavelength that comes from sun is not what is really absorbed. That radiation hits the earths surface, and is radiated back at a different wavelength that CO2 can absorb. Once the CO2 absorbs the energy, it can radiate it back to earth again. Greenhouse gasses is the reason earth is warmer than a planet like Mars. Mars long ago lost its magnetic field which allowed solar winds to blow away any greenhouse gasses. So, any solar radiation that hits the surface is mainly reflected back.
So, its not a question if CO2 holds in heat. The only question left to answer is how much can we release before we see negative effects that outweigh the benefits.
Also, I cant find anything supporting your claim that half of the CO2 stored on earth has been released. I would bet its likely because we simply dont know how much is out there. If you are trying to say that we will burn through all the fossil fuel before global warming would be a big issue, then that is probably the most dumb argument I have heard so far. its true that fossil fuels contribute to the vast majority of CO2 released, but its not the only source. Can you support your claim that we have only gone up 1 degree and have burned half of the fossil fuel supply?