I think you never see it referenced anymore because it's regarded as redundant and unnecessary. It used to be marketed as a 'Halloween event' (reference to a 'halloween event' in this media analysis from around 2013-2014)
This vlogger uses halloween in the video title referencing a fright nights event, and the comments include things like "i'm going this year for halloween"
Overseas, (which i'm sure many here would agree is the inspiration for such an event in the first place), the parks all do it "for" halloween, and many of their events include 'halloween' in the name. Its also probably indicative that the intention is to associate it with halloween simply because it (and several other events around the country) are all timed to occur on, or around 31 October.
I'd argue many people connect fright nights to halloween, given the multiple years worth of effort MW has put in to building such a horror and scare themed event in that manner.
No. Pretty sure @Tim Dasco or @iwerks can confirm, given their conversations with the GM, but Perth seems to have terrible weather around October, and many events around then are impacted - so the move to Feb\Mar is to have 'better weather' for the event.