Process creating

[Blesson Paul]

hi all
                      I have in a confusion regarding the creation of
processes by the kernel. Let I have two processes P1 and P2, both are childs
of P0. I want to know the following facts regarding P1 and P2. I have created
two processes by forking. Everyone knows that when P1 and P2 created, they
have different process spaces. 
1  If I point  to a address 0x434343 in P1 and  P2, will it point to the  
same memory area.
2  If not, I need two processes to use same process area, how to do that
3  Will linux kernel support threading
                            Actually I first thought about shared memory. But
for my application, I need huge memory area upto 50MB or more. So 50MB of
shared memory is no good. So I looking for any other alternatives

                       by
                                  Blesson