This is spiraling out of control.
First, this is all standard maintenance that should have been done over a long period of time leading up to now.
Second, the firmware and driver updates only take 20-30 seconds, then a reboot (except for maybe the iDRAC firmware, which might take 5-10 minutes) and shouldn't impact your timeline at all. It could also be done in advance of the OS/ERP upgrade (unless you are doing it NOW and don't have time for preliminary discovery/preparations).
What versions are your drivers and your firmware now? BIOS, iDRAC, PERC firmware? PERC driver? Maybe we can give you a better idea what to expect, based on what you are working with.
Alternatives? Build up a 2008 R2 VM and rebuild the ERP server from scratch. P2V conversion to VM that you can then play with/upgrade without worrying about drivers. Delay the ERP upgrade. I'm not sure you have many good alternatives.