So Ray who was Rank 1 in NA left the server, so Arc is back in Rank 1

It wouldn't surprise me Ray had a very one dimensional style of play that made him very predictable and easy to shut down. It's simply not something that makes for a good professional player. It wouldn't surprise me too much if they picked up a new top laner, or even just used Cris who is technically on their roster anyway.

Possibly. Many players do go out-of-region for the long offseason though, such as Piglet last year. It's quite possible that he just wanted to head home to South Korea while there was nothing going on for the team and come back when IEM and LCS preparations were happening.

From what I recall, all of Apex pride was actually kicked out of their gaming house once they didn't make playoffs (hence why crumbz is doing lcs-casting stuff now). Considering Apex didn't make the playoffs either, it wouldn't surprise me if the team was "sent home" as well.