I am confuse about memory configuration, i have below questions.

1.if 32-bit os maximum virtual address is 4GB, When i have 4 gb of ram for
32-bit os, What about the virtual memory size ? is it required virtual
memory(disk space) or we can directly use physical memory ?

2.In 32-bit os 12 bits are offset because page size=4k i.e 2^12 and 2^20
for page addresses What about 64-bit os, What is offset size ? What is page
size ? How it calculated.

3.What is PAE? If enabled how to decide size of PAE, what is maximum and
minimum size of extended memory.

Regards,
Pankaj