I have installed nvidia proprietary driver on livecd.
Will it break the 3d support for free drivers like intel or radeon etc?
The system is 12.04
No, on systems without an Nvidia card, the proprietary driver should not break the open-source Intel
No but why would you need more than one graphics driver ? You can do what ever you like on a live CD as nothing is saved, so you can mess around as much as you like on the CD, if you break something just restart the CD. The point of the CD is just to try it out. If you want to use one CD on different pc's you will have to start from the default set up every time. Also you can remove the driver the same way you installed it if you do have a problem.
You should Google "Ubuntu live USB" I think this is more what you need if you want a portable version of Ubuntu.