Hi Fabrice and Eric,
A long over due response. Apologies.
I got a unanimous answer about not putting the conditional statements in the code block header, that was reassuring =). I guess the use case here is if you have different configurations for different users or machines or something similar.
I looked at the code I was shown. I noticed there was some pieces missing but even though adding them I could not get the code to work properly. I figured it was due to me using el-get for my packages and no packages are actually required, but somehow autoloaded instead, by the el-get setup, or it's just a matter of me being a noob elisper.
Anyway, when I was fiddling around with the code I stumbled upon el-gets built in functions. I noticed that, of course, el-get has functions for checking install status of packages. My current solution therefore looks like this:
(if (el-get-package-exists-p "<package>")