I'm not sure which point 4 you are talking about. Connecting the gas lines together or connecting the liquid line and it having some beer pushed into it? It works just as good if you equalise the pressure in each keg, connect the two gas lines to ensure this. Connect the liquid lines to top keg then bottom. If it hasn't flowed, then disconnect the bottom gas disconnect, pull on the PRV for a short burst and watch the liquid line. It should fill with beer and flow to the bottom keg. Then reconnect the gas disconnect to the bottom keg so the gas has a way out. Robert's your mothers brother.
It's a siphon, so yes you will need the last of the liquid in the keg being transferred from, higher than the top of the keg being transferred too. If it's only slightly higher it will only work until the liquid levels equalise in height and not work any further.