Hi Yared,
1. On which Lunix distribution is Koha best for installation and Usage?
I think a lot of people here use debian for koha, but at my institute we are running suse. Basically most linuxes should work, as long as they come with the right versions of software. (mysql4, for example)
1. What are the dependencies and from where could find them? only from the Internet or from the Installation CD of the Operating System?
For dependencies, see the documentation here: http://www.kohadocs.org/ I always prefer installing as many of the requirements as possible from the distribution media. (because that way security updates happen 'automatically' with the operating system, and you don't have to keep track of those yourself) However, not all requirements are included in the distribution, so you have to download some from the internet.
1. I saw From koha site and the information given is not that much on dependencies. From where can I find detail list of dependencies and detail installation steps?
http://www.kohadocs.org/ -> http://www.kohadocs.org/Installing_Koha_on_Debian_sarge.html Good luck! Mourik Jan