"I know that SuSe was based on an old Red Hat ver. and that it is an RPM distro, but will Redhat or now Fedora's packages work fine on Suse or it will cause trouble??"
Red Hat and SuSE set up their file tree differently. So if you install a Fedora rpm on SuSE or vice versa then the files may or may not be installed in the correct place to work properly.
Also when installing any rpm you have to check that it uses the same version of glib as the system that you are going to install it on. Usually instead of the glib version the rpm lists the gcc version used to compile it which is effectively the same thing. This means that rpms compiled on one version of SuSE will rarely work on another version of SuSE. It is also possible for the latest version of Fedora and the latest version of SuSE to be compiled on different versions of gcc and thus be mostly incompatible.
My experience with foriegn rpms is that the odds are against them working, but not overwhelmingly so. When I am in the situation that I cannot find a rpm package for my current system I first try to compile the tarball and use checkinstall to convert the tarball into a rpm which is 100% compatible with my system.
http://asic-linux.com.mx/~izto/checkinstall/
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Steve Stites