Need help to upgrade BIOS on Optiplex 380.

Optiplex 380 MT (New, Refurbished)

CPU: DuoCore E7500 @ 2.93; Rated FSB:1064, Bus Speed: 264.0

Windows 7 Pro x64

It is at Version 3. Need to do an Urgent upgrade to 4 and then to current, V A07. Need to use a bootable flash drive. Could use some best practices re simplest/best boot-creating utility, caveats, need for signed firmware action (?), etc. I'm assuming since it will done in DOS that updating chipsets/drivers are not relevant. What about hardware firmware. Thanks. Thanks.

btw, Are there any peculiarities vis a vis these BIOS  upgrades that the Pro version presents ? Should I pause/stop Bitlocker if enabled like suggested on my Venue 8 Pro tablet (BIOS) upgrade ?