Copies of the 1965 book "History of Changi" by Sqn Ldr HA Probert, seem to be currently available.
I found this very authoritative personal account of Norman Quinnell's time in the RAF from 1943-47.
https://sites.google.com/site/nvquinnell/home2
It includes chapters on his service at Changi in 1947-47 (F/Sgt in the operations and movements depts) and describes the activities, aircraft and personalities involved.
ISTR pre-war, the Brits had correctly assessed the number of frontline aircraft (700 odd) and other forces required to defend Singapore and Malaya, and then utterly failed to provide them. Also it was said that while looking for suitable aerodrome sites, the Changi area was dismissed as wholly unsuitable, although there had been a military camp (on what became the RAF base's domestic/technical area for some years.
The "Johore" artillery battery at Changi consisted of two twin 6 inch mountings and three single 15 inch guns located somewhere around the top left hand corner of the current airfield - ie in the NW quadrant of the old cross runways.
The RAF Changi Association
RAF Changi New Website has a large archive of photos. There are thumbnails at the bottom of each 100 pix and include several aerials of the field at various times.