Is the Cisco Unified Communications Manager available only for Linux?
Yes. It's a sealed appliance model and you have no access to the underlying GNU/Linux OS. As such, you do not need Linux sysadmin skills; everything is done through Cisco-specific GUI/CLI interfaces.
How do we get the developer (login, password,etc) credentials for development?
Development of what? Cisco posts all of the developer-focused documentation on developer.cisco.com.
How do we make the application live so as to make and receive PSTN,etc calls over ISDN. Do we have to get our own telephony gateway?
Yes; typically this is a Cisco ISR. CUCM will work with most gateways that support SIP, H.323, or MGCP signaling. Note that CUCM is not intended to be externally facing (i.e. no direct SIP trunks to carriers). The recommended design is to use a Session Border Controller such as CUBE between the ISP and your LAN/WAN.
What are the charges for the same (i.e. the CCM charges,etc)?
You will need to work with a Cisco partner to generate a quote to you. We cannot speak to the specific costs/discounts that would apply to you let alone cover enough details on this thread to make an educated cost that adequately.
What are the facilities provided?
Please clarify this question. What facilities are you referring to?
