Hutzpah:
Which ground do I plug into as there are two?
One in the bottom right hand corner and another just above.
Use whichever ground is most convenient to you. I prefer to use the USB to TTL serial adapters that use the "FTDI pinout" that allows you to plug it right in to the Pro Mini, like these:
Robin2:
This reference page suggests that it is the FTDI RTS line that is used to reset the ProMini - but maybe your stuff is different
You can use DTR or RTS for the reset signal. Some of the USB to TTL serial adapters that are pinout compatible with the Pro Mini use DTR, some use RTS. Adafruit chose RTS. Sparkfun chose DTR.