SanDisk Extreme SSD Firmware R211m download for for MacBook and MacBook Pros based on NVidia MCP79 chipset

hi all, 

i’m running a mid-2009 17" MBP. have purchased my extreme SSD 240GB - ready for installation now.

first of all, i understand the firmware upgrade is best done before installing or cloning the OS - has anyone had issues doing it afterwards? (either way, i will of course have a backup.)

i also understand the firmware upgrade will not work if connected externally - as in, the SSD needs to be connected directly to the motherboard through the SATA in order to upgrade.

please correct me if i’m wrong on those points.

must the update be done with a CD/DVD of the saved image file or is there another safe way of doing this? perhaps a USB flash drive?

also, if the CD/DVD option is the only reliable one, what does it mean by ‘burn the saved image file to a CD/DVD’ - is the saved image file simply the enzo-r211m-240gb.iso file I downloaded? or do I need to extract something in particular from that file?

many thanks!