I have nearly 800 MB of .deb files in cache folder .... I went through other posts related to this query but I wan not convinced. Should I just save all theses files somewhere ? I guess it won't affect anything !!
No, they are not important. You can remove them safely. Those files are just like the name says cached for later use. That means that if you installed some software and later removed it, you do not need to download the package again,but just install it from local debian package.
To clear the whole cache use
sudo apt-get clean