question about multiple server setup

[Evert|Rooftop]

Dear list,

First, thanks for this great product, can wait to put it in production. 
I have a question regarding the setup for our situation.

We are using PHP on all machines with the PECL extension, furthermore 
the extension is abstracted, so in the case something fails the 
filesystem takes over.

We are having 3 webservers, with a bunch of extra (older) boxes I could 
use for memcached.

 From the PECL extension I can add multiple servers to the server pool. 
To clarify my question, I'm naming the webservers www1, www2, www3 and 
mem1, mem2, mem3

Possible setups:
www1 uses a memcached connection to www1 and mem1
www2 uses www2 and mem2
www3 uses www3 and mem3

or.. can I add in all my servers in one big pool and make my webservers 
all share the same pool.

Also, I have a bunch of other questions.

1. lets say I have 80 apache forks, if I would use the big pool this 
could mean I could end up with 80*6 = 460 open sockets.. Is this feasable?
2. Are all servers accessed to see if there's a cache available, or is 1 
server picked for every request
3. If for every request 1 server is picked, do I need to replicate data 
across servers?
4. If only 1 server is picked, and this server happens to be one of the 
older boxes (with less memory) does this mean 50% of my requests have a 
smaller cache to work with and will therefore be slower?

Thanks for your help,
Evert

-- 
www.rooftopsolutions.nl