Were the use of mouse-over macros, custom raidframes and addons similar to HealBot common then? Or was most common method simply clicking?

Grid/Raidframes.

Also, lots of downranking of abilities for mana efficiency and also to avoid overhealing. I did an RFC and even then I was mostly using a lower rank healing wave for mana efficiency and to keep the tank topped up, rather than having to wait til he was 50% to avoid overhealing with max rank heal.