Does IPMI always include KVM? Is it always able to mount remote .ISO's and show viewport image?
IPMI is not KVM, see http://en.wikipedia.org/wiki/Intelligent_Platform_Management_Interface . The basic functionality of IPMI is to provide the hardware status (on/off/restarting/faulty) and to power the machine on and off. Lastly, IPMI can send some basic SNMP traps.
KVM (or rather in this case IP-KVM) is a remote management on a higher level, which includes IPMI functionality (though there are some older KVMs that use their own protocols), and also the over-the-network passing of keyboard/video/mouse so the physical server console can be remotely accessed. Remote ISO and floppy mounting is yet another functionality, and not every IP-KVM has that.
No, not always. These days it is rare that it is not included, but I have some old servers at home where it does not include KVM.