Yea you basically figured it out.
Yes the ‘open’ cable clamps into the connector just fine. If you are worried about it wiggling loose them tape it down.
If the connectors were laid next to each other the pins would connect up directly across. If that makes sense. So whatever cable you have has to reflect this.
Off the top of my head that should be a ‘straight’ cable. A reversed canble would require you to flip the cable thus reversing the pins.
Iirc the ipex pins are actually on the bottom, even if it doesn’t look that way.
Hope that makes sense!
You can always buy both as they are so cheap and see it practically laid out infront of you.