Please tell me that 16GB of internal storage as mentioned on NEXUS 4 is available for apps or for apps it creates separate internal storage thing as it does in Nexus S...
No device can have all of its internal storage free for user. The Operating System (and pre-installed apps) needs some space for itself. So Nexus 4 doesn't give you 16 GB free either.
The 16 GB version of Nexus 4 gives user an approximate of 12.92 GB free. Whereas, the 8 GB version of Nexus 4 gives you an approximate of 5.67 GB free space to use.
I don't have the device (at least yet). This is what I have found in reviews / discussions.
I have a 16Gb Nexus 4 and I can report that settings -> storage indicates a total capacity of 12.92Gb. There does not appear to be any restriction on how this is used. It's possible that there is some hidden limit, but if so there is no indication of such. It seems very likely that you can install as many Gb of apps as you can fit on there :-)