Will my windows 7 applications works on Windows 8 Release Preview? I have the chance to upgrade, my laptop will support it. But i dont know whether to do it or not? will i be able to keep all my windows 7 programs?

Do not upgrade your installation. Set up a dual boot and install Win 8 RP in a separate partition. This will allow use of both OS's.

If you upgrade you will loose the Win 7 apps and have to reinstall them as this upgrade requires a clean install. With the dual boot you can have both. This is the only way to go with a laptop. Then you can install just those apps you will actually use on Win 8 RP.

This is a time limited beta OS. It will deactivate shortly after Win 8 goes on sale this fall. Do not overwrite your Win 7 installation!