Running a PAE kernel on 32 bit is pretty standard at this point, I believe. Please correct me if I missed something.
It has nothing to do with PAE, but 3G/1G split I think is default on Linux.
That does not address the 512MB of virtual address problem, which is not an issue with PAE.
Yes it is because PAE doesn't change the address space of processes. PAE let's you use more physical memory, the address space of each process is still the same, because 2^32 is still 2^32 with PAE.
It seems Windows bashing without any background knowledge is becoming popular again -_-