Can I add Ubuntu 12.10 repositories to 12.04 to have the latest software and updates? If, yes, how can i do this? I know that by adding PPAs I can have latest software, but really, I do not like to use PPAs. So is there any way to use 12.10 repositories in 12.04?
If you want you can add them in
/etc/apt/sources.list file. But, be warned that, you may face dependency conflicts later. Also adding them is like running 12.10 without upgrading. But anytime you execute the upgrade command, the system will be upgraded to 12.10. So, there is no benefit adding them to 12.04 without using the upgrade instead.
If you wanted to have an upgraded version of some apps only (and wanted to remove the 12.10 repos after doing that), then I strongly advice you not to do that. Because upgrading to an updated version will/can put your system forward and after removing the 12.10 repos, you'll face numerous problems with dependency from the non-upgraded packages.
You can add other repositories, including for future and past versions of Ubuntu, to your
/etc/apt/sources.list file or new files in
However, this is not recommended. Ubuntu does not do testing of packages across versions and you are very likely to encounter undocumented conflicts and errors if you do this. If you want to mix and match repositories I would recommend starting with debian testing as your base OS and then adding Ubuntu or other distros' repositories on top of that.