Evaluating Memcached for our site. Looking for advice.

[Jason Gross]

I am evaluating memcached for our web farm and wanted to poll this  
list for some experience in designing, deploying and maintaining it.  
Specifically I want to analyze the overhead from a development /  
resource and maintenance standpoint so that I can properly plan this  
effort. Would anyone on this list be willing to share their  
experience with deploying memcached?

The site I am working on is a social networking site that users can  
upload individual products which other users can comment on, purchase  
etc. The site is growing quite rapidly and is beginning to show  
significant slowdowns during peak periods. I have a decent  
understanding of what memcached provides and feel that its compelling  
enough to give it a try as there are a significant amount of database  
queries on each page load. I'd be interested in any feedback but have  
some specific questions below of what I am looking for.

1. Are there tools that exist to help analyze which queries should be  
cached?

2. What exists  to monitoring and analyze for cache performance on a  
daily basis?

3. What level of effort was required to integrate memcached into the  
application?

4. What was the support overhead from a time and expertise standpoint  
to maintain this?

5. Are there any issues or problems in integrating and deploying the  
cache that are non-obvious or particularly time consuming?

7. Are there any hardware requirements for the cache servers or  
specific hardware that perform much better in a highly loaded  
environment? (Perhaps specific NICs that do better then others)

Thanks!
-Jason