@JasonCramer the goal of putting questions on hold is to avoid unhelpful answers, it is by no means intended to shut you out. So feel free to edit your question based on the feedback you got and the information from the Help Center, it will then automatically get placed in the review queue for reopening.
I assume you are referring to one of your answers (didn't find any questions or deleted answers from you), left a comment there.
Going to fetch an older iMac in a few hours: It's old enough to have 10.6 (Snow leopard), but new enough to have a pretty flat display. I need to update it to at least 10.11 (Maverick). I was asked to reformat it as well.
Anything I should know? Will an OS-update cost money? Do I just turn it on, connect it to the internet, and Apple does the rest?