I am not an expert, but I am only an hour away from you. It looks like you have buds from the picture. It will be another month (?) before they bloom. Rhododendrons set their buds in the late summer or fall. Be patient. Probably the plant will grow into those tall shoots. But, I only have personal experience to judge by.

A couple of things are going on. Photo #2 is showing rhododendron leaf spot, Septoria azaleae. Photo #3 & 5 show lacebug damage, not aphids. IME, aphids seldom bother any broadleaved evergreen. Don't really see any yellow foliage. New growth typically comes in a much lighter green, almost chartreuse, but will darken as they mature.

Just a common old garden spider.....nothing to worry about and nothing to do with whatever may be ailing your holly (not a Japanese holly, btw). Garden spiders are good things and should be encouraged. FWIW, hollies can be cut back hard and they will backbud or produce new growth from bare stems. Your plants look perfectly healthy otherwise and with no sign of insect or disease issues so why they are so leggy and sparse now is most likely due to cultural conditions....lack of water at some point, possible cold damage at some point or issues with the root ball when planted.

Looks like a big old 'semi-ironclad' like 'Lord Roberts' which were once commonly planted as (street) trees in NZ & AU. Since fire is not a common issue in Rhododendron growing regions of the US, I can't specifically say I know what issues it causes long term with the plant. This plant looks generally healthy. Was it once more shaded than it is now? Depending on where you are in AU, a full sun exposure may be too much for it. Was it exposed at the roots to ash debris? I wonder if the alkalinity of ash could slightly raise soil pH, which rhodies don't like, and tie up nutrients, which would account for the slight chlorosis. In that case, LIGHT application of a fertilizer designed for acid-loving plants like rhodies and blueberries, could be appropriate. @shaxhome (Frog Rock, Australia 9b) any ideas?