Optimization questions

Specs: Server RedHat 7.1 2.4.2-2 kernal everything build with Interchange
4.8

I am learning Linux and Postgresql from scratch.

1. Can someone point me to or explain any linux kernal optimizations for
redhat that can made to maximize performance of a postgresql server? I
have briefly looked at Momjian's performance recommendations for the
postgresql database itself, but I wondering if there is more that can be
done?

2. What RAID levels does postgresql support? I don't want to make any
assumptions. I plan to put the data on an EMC Clariion FC4700 with RAID
10 eventually.

3. How much memory does postgresql require? Is there a best known method
for size of memory in relation to the size of the database and expected
growth rate? Is there a way to optimize memory i.e. page free space and
page splitting - this may not be applicable but I have been tasked to
research it.

4. How is Symmetric Multiprocessing Processor (SMP) configured? Can
postgresql take advantage of SMP?

Thanks,
Jeff