For Arabic and Hebrew you need a MENA version of InDesign, Middle East North Africa
For Chinese you need an Asian version of InDesign.
When you are not in the cloud, you have to buy extra these versions for a complete price of each.
When you are in the cloud, you can install those versions extra without additional cost. You can install them first in English (or whatever your first language is) and then change in the CC Desktop App the application language and chang it in an additional language. That will add more functions in your first installed version.
I would strongly recommend to install only MENA or Asia additional on the same computer, as installing them on the same computer at the same makes InDesign not stable. But you can install MENA on one Computer and ASIA on the other and work for each language with the same document on different computers.
We can also use World Tools Pro (plugin Hebrew, Arabic, Indic languages, Chinese, Japanese, Korea), but we know nothing about it. For small tasks will be ok but for large?
Indeed installing two versions on one computer is a bad idea (option is virtualization).
If we buy CC there will be any Arab or Chinese fonts (MENA versions had them)?
Is the operating system and the selected language may have an impact on the options available in InDesigns 6?
CC versions can run parallel. I would suggest to deactivate and uninstall CS6 before installing CC versions as CS6 (in a better form) is also available as CC, CC 2014 and probably soon a 2015 version.
You can install several language versions in one installation, that is not the problem, it is indeed recomnden and the good way. The problem is only, if you have MENA and ASIA versions installed it causes often crashes. No problem is, to install English, German, Hebrew, Arabic, Farsi on one computer and English, German, Japanese, Korean, Chinese on another computer.
It will always take the UI language of your OS if available. Other functions are added.
Yes, with installing those versions additional fonts for those languages are added, similar to Myriad and Minion style.
You can run different versions from CS 6 to CC 2014 and probably 2015 parallel on the same computer.
Thanks for your answers.
This means that we can install on the same computer CS6 and the new CC, but it can be version of "Arab" or "Chinese" (not together).
Will we be able to switch between the CC after the installation version of "Arab" and "Chinese"?