linux quries

Hi Experts,

I want to know how to install dual linux OS in the single HDD partition as like a dual Linux

for example like windows xp i can install in C:\ and

window 2003 i can install in d:\ like wise i want to install the LINUX ditro on with RHEL ver and another with Fedora...

2. i want to check which Linux distro i am using like debian with Kernel or rhel with kernel without the file cat /etc/release anyother i can check version.

3. In my system /etc/passwd file got corrupted/deleted i dont have backup i want to recover the file what are all the possiblities are there?

4. what is the port no for nfs,portmap...and use of nfslockd