An "official" Arduino schematic would be obtained from Arduino, not Sparkfun.
a power isolation jumper
Pro Mini clones cost only about $1 on eBay,
. . .I'm actually not a big fan of the SparkFun style of Pro Mini. I really like the Chinese ones that have all pins on grid and even manage to squeeze in an ICSP header! That's the only style I'll buy now.
OK, I exaggerated about "all pins on grid". The "FTDI header" is not on grid. That doesn't bother me because I don't ever need to connect that to a prototype board.https://www.ebay.com/itm/352036437846I think you can find them a little cheaper on Aliexpress, but I've been burned too many times now by the horrible sellers on that site so I've decided I'd rather just pay a bit more on eBay and actually get my orders.