The fact that this is your domain controller is irrelevant (assuming you maintain good backups and plan your maintenance downtime appropriately). 
Hi, I've got this server and i have not updated anything on this server a long time. my OS is windows 2003 r2 32bit server. I am planning to install windows 2012 r2. what should i do first? do i need to update the hardware such bios, firmware and etc.? can you please show me the steps on how to update my PE server 2950 please? thanks in advance.
Power edge 2950 hardware