Memcache implementation

I have a Wordpress site that uses WP Super Cache plugin in order to make my blog posts and pages stay as HTML so that less PHP/MySQL code is executed. However, there's a featured box that can't get cached. So, I configured it manually to bypass cache and stay dynamic (code is executed on every page load).
So, most part of the entire page is executed using HTML and a specific part (a featured bar box) uses a PHP/MySQL.
The code that runs on every page load are some simple ` to select some data from my database and some $fetch and ` to print the results in the webpage, of course. But instead of everytime calling database to get this results, it would be much better to cache this results. So, I have three options: 1. Let WP Super Cache caches my entire page. But I can't do that, because inside my box that currently isn't getting cached, the database data can change anytime (normally 1 time per day). So, I can't cache this box and we have to discart this option 1. 2. Activate query_cache in my.cnf. However, this will only cache MySQL and don't PHP. :( 3. Than, we have memcache (or APC, I don't know much about it's difference). After all my explanations, here's the final question: I'd like to know if installing memcache in my server is enought to get it working imediatally or I have to make any changes in my code to adapt it with memcache; I'd like to know if it will really help me with both PHP and MySQL for this specific part of code I have to cache or it's results is similar to enabling query_cache? Or is using APC rather than memcache better in my case? Thanks,
André.