I m using a Different control panel.Can I run H-Sphere jointly with another control panel ?

No. In order to install and use H-Sphere, you need to uninstall or stop all other control panels.

Can H-Sphere be installed on a Cobalt RAQ4i Server?

This depends on the version of Linux. If it is RedHat 7.2 or 7.3, H-Sphere can be installed, but the services that come with the server are not compatible with H-Sphere and need to be disabled.