* Disclaimer: I am an employee of Alphabet or one of its subsidiaries, but I do not work on this team, and didn't know anything about it prior to reading this article.
JP-7 has a very high ignition temperature (it was actually used as a coolant/heat sink for the rest of the aircraft), so TEB combusting once it hit the air is used to light the engines.
SR-71s only had a limited amount of TEB to use each flight. I believe it was 13 shots per engine. TEB was used each time the engines were lit and also when afterburners were lit. While the SR-71's routes were built around refueling, the number of TEB shots remaining were the true limiting factor of the SR-71's flight time.
Note: I'm not affiliated with Veertu, but I recently came across the product and found it very interesting. If you're interested in OS X's Hypervisor.framework, it was added as part of OS X Yosemite: https://developer.apple.com/library/mac/releasenotes/MacOSX/...
PowerPC Macs (in the 2000s, before the switch to Intel) did indeed require a manual step to update Boot ROM/firmware - a different mechanism than resetting the PRAM. You'd run the installer, then either shut down or reboot the Mac. As it booted, you'd either hold down the power button or the interrupt button (depending on the model) to initiate the update.